Here's what I have learned as a very novice hobby lathe and mill user. I have a busy bee 9x20 sieg lathe, good support on the users group and worth doing all the updates they recommend. Buy good quality stuff, research it, use ebay like others have posted. Buy hss cutters in different sizes and dedicate a bench grinder to making the shapes like others have posted. After throwing money away on indexable cutters and other insert cutters, I have abandoned them. They may look versatile or even long lasting but I had nothing but trouble with them, likely due to buying the cheaper ones. If you can build holders and boring bars rather then buy them, well worth the experience. Make sure your machine is as ridgid as possible, follow the constraints of your machine, as in do not feed more then your machine can handle. A great source for manual lathe books used to be lindsay publishing but they have gone out of business, Dave Gingery's son still sells his books and they are great for learning how to work a lathe and use hand tools to make well the whole machine shop. I have the whole set of books and looking this up just saw that they have the set in hard cover.
http://gingerybooks.com/
As I have no formal training in lathe use this is all but my personal recommendation.