www.3riversarchery.com , in their hunter's den section, has a bunch of free video shorts you can watch that show you the basics such as...
measuring your draw length , to how to install string silencers, etc.
imo. you are on the right track if you get a good used bow. Because, you can get a higher quality, bow with better performance and quality workmanship for less money.
On the other hand, don't knock a good mass produced bow, such as the Bear Montana longbow, the Martin savannah, etc. the only thing these bows don't have that a custom bow does, is getting to choose the option of riser/limb woods, and bow length.
I you have any questions, just pm me.
sammy