What kind of business should I be and how should I file taxes?

[Leah Ezra]

I have always had a clear vision of what I wanted to do, but I finally have the time to educate myself and really get started with my business. 

My husband and I would like to go into business together, so whatever way we file taxes I'd like to do once a year for both of us. As of now, I am looking into getting my tax identification number, and a business license. I have an online clothing store that I'm in the process of building. It's become a hobby of mine, as well as an income source. Eventually my plan is to use the store for income to invest in real estate as well as other investments. I want to know how I should go about my taxes and write offs, so that I am able to use money rather than really spend it, and what I should state my business as (an llc, corporation, or sole proprietorship)? What do most REI's claim their business to be?