Any Useful Adobe Illustrator Tutorials?

I’ve spent the last week or so looking for insightful tutorials which’ll aid in UI design, however I can’t seem to find many, as they all go into app design, rather than game design.

There is a great tutorial on Illustrator by @younite and you should definitely check it out: Younite's guide to Illustrator

There is also a youtube tutorial which gives a full overview on Illustrator: