Merchanting - Where to begin?

I've been cringing at the idea of merching again, but there's just no reliable way to make money anymore...so as the title says, where does a new merchant start? I haven't followed the market in over a year.

I'm poor as hell, but let's pretend I have 1bil. What is good to buy? Chairs? WGs? Or just go FM surf and look at things for ideas?

MTS merching is also an option, but I've never really understood that.