visit your local small business development center. most cities have one or two or three. they'll give you everything to get legit, help you with competition strategy, and be honest with you about any flaws.
Also, work with other businesses. Sell complementary products. Call up the fitness clothing store, offer to keep a rtack of their stuff in your store for a markup or %. If you do this with 5 stores, you might have an awesome, maintained inventory of vendor goods without having any of the risk.
As many ways to get $ flowing in as possible - that is the goal. Remember that most people only have ONE source of income - their job. To me, that's crazy. I have many clients and several different fields that I work in at the same time - if any industry or client craps out, I still pay the bills.
Good luck to you! 90% of small businesses fail - the other 10% just work smarter AND harder, and above all, they pick something they love in the right field.