Here is my two cents worth:
Stick to the 1/2 off rack, end-of-bolt and clearance for a while and only buy from those racks the fabric that is absolutely screaming at you!
You will buy less of what you don't need, if you need to be careful with spending (I am still trying that one!)
Eventually, your stash will get its own look as your taste in colors and patterns emerges.
When you buy, buy at least a yard and try to buy at least two fabrics that coordinate.
Several comments about focus fabrics, good background fabrics, and general purpose patterns have been excellent. If YOU think it looks like a backing fabric, then you just Know you need a really big piece.
Have fun,