honestly, you draw good, high school level in this piece, it is composed ok, decent flow, other aspects need some work,
I would suggest you do as I did, join a local college art class, if your lucky enough to have a good one close an art college, even if all you can take is weekend class,
you will find it very valuable to see where you are compared to other locals, you will see where you are lacking and where you are ahead of the curve and you will learn so much more working with other people who are better than you and having a teacher,
many artists you seen in the magazines every month started this way including many who have worked on me and some I call friends,

same with apprentiships, there is a big difference between tattooing your own leg with an ebay kit at home, to getting to apprentice in biker joe smiths super street shop and bong emporium or an apprentiship with Brandon Bonds All or Nothing or the like………….put your self with the best you can, you will develope faster and learn more

to be honest I never used them, I bought books for reference, western style stuff , classic pinup, cars, planes, animals and used them for reference, believe me working with other artists is the best medicine, you leanr so much and quickly too!