Here's my businsess plan for you.
Sell some stuff that is yours.
Then sell some stuff that used to be somebode else's -- garage sale, thrift store.
- You learn how to research and write about crap (this is the stuff you'll be getting, right? Crap.)
You'll learn about a bunch of categories of product (you really don't want to sell everything that is brought to you, right? A lot of it will really BE crap --" can you get anything for my Tony Orlando collection?")
You might find a specialty along the way (these consignment outfits do OK, but the 20%margins are relatively slim, IMHO - beef it up with easy, repetitive sales.)
By that time you'll have found and seen resources to make those small jobs easier (shipping, billing, tracking, hosting, templates.) And you'll be able to apply it on a larger scale. You'll have a reputation built up to insure better prices for you and your customers (20% of more is more.) You'll be able to decide if you can do this day after day -- wheeling and dealing is fun, but clean-photo-research-describe-post-answer-ship-placate&pay can get old. But I recommend starting now, not later.