Hi,
Start by only buying what you have a pattern for and plan on making. I find that by buying just because it's on sale with nothing in mind, that it barely gets used. It either isn't enough for what you want to make or you can't find the right blend of fabric to go with it. My stash is mostly left over pieces from different projects. You'd be surprised how quickly that grows, so my advice is to start slow and finish what you start. You'll have more money to work with when you get to your next project. Just my opinion.
Sandy