Best advice...don't.
Its a big gamble. But if you insist on doing it some advice I can give you is make sure you buy a POS (Point of Sale) System so that you can become a SoundScan reporter. This will help you get attention from major labels as well as free product and recognition when you do well with a particular release.
Good suppliers are:
UrbanLife (mostly indie but some major and lots of DVD's)
Super Discount (everything)
Norwalk (everything)