For a beginner, I recommend using Photoshop first. Familiarize yourself in simple pen tool (which can be very
complicated) then you can go experimenting in Illustrator... :) But since you have Illustrator already... which is a
very powerful and proper vector artwork program, one thing I can only say to you is to be patient and to follow those
tutorials. I myself is not someone great in vectoring but I learned that patience will really take care of the rest, and
of course hard work.
When you grasped the basics, then nothing else will be very hard for you. I tried vectoring once and continuing now...
it's fun. :D
Sorry if I haven't helped you much but I hope someone (hopefully, an Illustrator user) else will comment
here.
Let's both do our best in vectoring! *CHEERS*