Illustration

Hello and sorry for the late reply! 

There are multiple ways to learn illustration. I'm assuming you have no experience with Illustrator so my advice belove is based on that. Feel free to skip those that doesn't fit you. 

First to learn Illustrator the behance creative challenges is a great way to familiarise yourself with the different tools in Illustrator. Each challenge typically focus on 1-2 tools or effects. You can spend as much time on each challenge as you like. To see all the challenges go here:  https://www.behance.net/challenge/illustrator 

When you are done with a challenge, or you have questions about something you need help with during the challenge you can post your questions in the official Adobe Illustrator Discord. It's also a great place to post your other work for feedback or if you are stuck and need help: https://www.discord.gg/adobeillustrator 

I hope this helps!