How to shade properly in Illustrator?

The best thing to do is get a lynda.com tutorial account and search the tutorials for TWO things.

1.  Deke's Techniques, Gradients, Illustrator

How Gradients Work In Illustrator Cc

2. Gradient Meshes.

Creating Gradient Meshes with Illustrator | Lynda.com

Look those up

(learned it from the tuts)

Learning to use the Gradient tool is pretty cool.

Feeling comfortable with the tool bars on the left is what you also need. 

You can also start here this will help you understand. 

Illustrator CC 2015 One-on-One: Fundamentals | Lynda.com

Seems to people on this page want you to do it they way THEY had to bust their asses doing it.  Tuts are just as bust ass.  Depends on your learning style...

I have to say...JETalmage is being a total bad info, Jerk***,  Some people are NEVER going to read that 1000 page plus manual of Illustrator.  MOST of todays users are hands on learners, they learn from tutorials.  They also learn how to handle it through their own personalities.  But I bet you 90% of people dabbling into it will not read that manual.  Really dude?  It's got info but I'd rather count my sock drawer.

Glitcher3000 Shading is done by using Gradient Meshes.  Knowing selection tools is the key to Illustrator as I see it.  It acts very similar to PS in my opinion.  Just the selections tools are a totally new way of thinking...

I suggest you go to Lynda.com and do the first few chapters of Illustrator CC Fundamentals, I have been using it for years and it REALLY helped me understand Adobe.  Adobe is about the learning process of Adobe.  I think you should stick with both tho.  Just dabble with the Gradient Mesh's and screw it up over and over and over, you'll pick it up.

JETalmage gave horrible advise if you are starting off.  I say if you got the software, jump into it... It won't bite.

You might find these custom brushes useful. They are my solution to "realistic" shading in AI. Access them through "Brushes>Open Brush Library>Other Brushes". They can be customized further by changing the brush preferences once they are within the brush panel. They can even be set to "Pressure Sensitive" if you have a digital tablet (make sure you're using them with the "Brush Tool"). They offer a more "organic" approach to shading in AI. Change the stroke width and transparency settings to take full advantage of the brushes.

Free Transparent Fade Brush Set for AI Users - Ray Craighead, Illustrator

So i think the best answer is, if you want to shade like photoshop, your going to have to use photoshop- best thing would be to set up your artwork in actual size and then convert your vector art to pixel

All these snide comments are just unnecessary

Stop being so snide Mylenium. Most of your recent comments have been like this and they don’t help anyone. Seems you have a problem.

This is the most common of beginner fallacies: bringing completely erroneous assumptions that a program like Illustrator works like Photoshop. It doesn't. It's an entirely different world.

Because this subject is so often repeated here, the following is intended as "open" advice to all (at least those with ears to hear); not as an affront to originator of this thread or anyone else. (I wish something at least conceptually like it were provided as an omnipresent FAQ or even required reading to which to direct newcomers.)

(Apology for CAPS in the following. It's not in this case meant as yelling. I've used it in lieu of italics [for basic emphasis] because of bugs introduced yet again in the rich text editor of this forum.)

When starting out with vector-based drawing program (any of them, not just Illustrator), you are far better off FORGETTING Photoshop. It's an entirely different process for entirely different purposes. And the differences are for good and legitimate reasons.

I've watched a dozen tutorials on YouTube, but none of them answer my question.

You're just making it harder on yourself. Diving into online "tutorials" posted all over the web by other Illustrator users IS NOT the way to get started. Such "tutorials" are created by other users of all levels of actual experience. The fact that the subject of a "tutorial" looks like something you want to do is absolutely no guarantee that its author is any more "expert" than you, nor that--even if he is--has enough technical writing skill or dilligence to accurately describe the process, nor that the process being described is even best practice in the first place. If I had a buck for every online Illustrator "tutorial" authored by relative beginners giving other beginners downright bad advice (blind leading the blind), I'd be richer than Adobe hopes to become by abusing its customers with a rent-only licensing scheme.

The way to learn any software is to start with its official documentation. Read it start-to-finish, and work through every operation described as you go. There is no shortcut to this, and it IS the shortest path toward developing actual balanced proficiency. Don't trot out some bogus special case appeal like "I'm just not the type able to read documentation; I'm a 'visual' person," etc., etc., ad nauseam. If you can read posts in a user forum, you can also read the--yes, dry but at least RELIABLE--instructions in the provided documentation.

Forget the self-proclaimed "expertise" of everybody-and-his-brother's online "tutorials." Buckle down with the provided documentation and use the program according to its instructions until you have a strong foundational understanding. Only then dink around with "clever tutorials" because only then will you at least have some discernment as to whether the "tutorial" is accurate, complete, or even best practice.

The fundamental, bedrock, foundational difference between programs like Photoshop and programs like Illustrator boils down to this: There are TWO basic and very DIFFERENT kinds of computer graphics: Raster images and vector-based drawings. They are equally important. EVERY serious digital graphics producer should develop proficiency with BOTH. Think of them as two hemispheres of the entire graphics world. If you're only proficient with one, you are living blind to an entire half of your chosen endeavor world.

Mainstream graphics programs produce graphics in either of two ways:

• By filling a rectangular area with an array (rows and columns) of color values, completely "dumb" to any idea of actual "shape" (raster imaging; Photoshop and similar programs).
• By describing actual shapes in terms of mathematical formulae (vector-based drawing; Illustrator and similar programs).

Now, given that, wouldn't you EXPECT those two classes of graphics programs to work differently? Like it or not, they do and they SHOULD. One is not inherently more difficult than the other. Like anything else, it's a matter of first grasping the underlying concepts involved and then developing familiarity with the tool. You wouldn't expect English literature to be learned and executed in the same way one learns and executes algebra. You don't roof a house with the same tools or by the same methods used to paint it.

So set aside your initial frustration because it IS generally-speaking invalid (despite Illustrator's worst-of-class vector drawing interface). Don't condemn something for which you don't yet possess even the most basic conceptual understating because any assumption that you understand ANYTHING basic about Illustrator on the basis that you understand the basics of Photoshop is wrong. The two exist as separate programs for FUNCTIONAL REASONS, not just to provide some "alternative preference" for doing the same things.

I'm trying to figure out how to shade a drawing in Illustrator in roughly the same way I would in Photoshop.

Vector-based drawing programs are inherently OBJECT-BASED by nature. A vector drawing is essentially a stack of any number of discrete, individual, independent OBJECTS. Each object may be a path (mathematically defined shape), a raster image, or a live text object . By contrast, when you work in a program like Photoshop, you are basically engaged in creating just one SINGLE object (a raster image).

Because vector paths are mathematically-defined OBJECTS, things like color and gradients and effects are ASSIGNED TO them as attributes and commands. This is entirely different from merely re-coloring pixels (which are not discrete objects, but mere color values in the single rectangular array), which is all you're really doing when you "color something" in a raster imaging program. There's no "someTHING" to color; there's just a subset of the color values to alter.

If I select a surface,...

As you read and work through a program's provided documentation, pay attention to the terminology and force yourself  to use that terminology when discussing it with others. "Surface" doesn't really mean anything in Illustrator (except perhaps generically in reference to its 3D Effect), just as "Node" means something clearly defined in CorelDraw, but not in Illustrator.

...and pick a colour to shade with...

By the same token, when asking questions avoid making up your own language to describe what you're doing. "Pick a color to shade with" makes sense to you, but is ambiguous in the context of Illustrator; it can be interpreted as your doing any of several things in multiple very different ways. Always state what you are doing in tool-by-tool, command-by-command, click-by-click ordered sequence --again, always using the program's terminology.

Don't apologize for being a beginner. (We all started as beginners, and It will be obvious in your question if you are one anyway.) On the other hand, also don't appeal for special treatment for being a beginner. It's not an excuse for at least trying to use the program's terminology, because you have the same access to the provided documentation as everyone else did when they were beginners.

Their [tutorials'] method of shading is completely impractical...since they draw the outline of the shading with the pen tool on a separate layer. That's not what I want. I'm using a segmented character for animation, so the shading is very strict

Don't assume that the methods employed for one kind of drawing problem are "impractical" or "inferior" just on the basis that they're not best for your specific use. You can easily embarrass yourself with such assumed "superiority" when you find out that you're failing to understand the most basic things about the program. And don't assume that your use is inherently "more advanced" than someone else's, for example like the attitude frequently exhibited by users of 3D modeling programs who assume the "technical sophistication" and "complexity" of a third dimension (egads!) must surely render the use of a merely 2D program brain-dead simple. Their own assumption of "this has to be simple compared to what I already understand" becomes their own insurmountable stumbling block in learning.)

JET