Simple question: how to snap to lines, guides, intersections?

[mirafoto]

I ma drawing some clipping masks, shapes in illustrator. There is some design already drawn. I want that new shape corners alight to other objects, guidelines, etc. If I draw them vaguely by an eye only, then when zooming im I see that object starts 21.00009 mm when it has to be 21mm and often a hair thin line from another object layed behind will be still seen when in print.

It would be helpful if my shapes would snap to other objects, guides, whatever same way as it is in InDesign.

how can I sconfigue Illustrator in this way, and how to control this behaviour???

I have used Visio befoe and had no problems whatsoever. On new job, we have Adobe packages, but I do not see Snap to Grid, Snap to Guides in the menu. 

Thanbk you

[mirafoto]

so far it seen snapping but only when magnified at pixel level, otherwise not working, and automatic guides do not appear. 

[mirafoto]

in another corner of the shape snaping did not work, so control point and clipping mask vertex did not snapped to the page corner, I did not known this until magnified. Vertex did not want to snap to the intersection of the guideline and page no matter I try. everytime I magnify more I see it is missaligned.

What I am trying to accomplish is shown in another image, I want clipping mask for metal gray plate (jpg image) above portrait to be same shape and size as a table below. It is simplest task, which seem to be difficult in Illustrator. 

[Monika Gause]

Snap to grid or point is in the View menu.

Have you tried out Smart guides?

[Mike_Gondek]

enable smart guides

view >> smart Guides

then grab by the point and drag it will snap based on snapping tolerance  set ehre

Illustrator is very advanced in snapping, you can also snap to glyphs now. Here are where all your options are