Craigslist is your friend.

There’s a lot of trash on Craigslist of course, but you can still find a mechanically sound bike for $200-$300. Get one without breaking the bank and ride it a bit. While you save your money for a “real” bike, you’ll have lots of opportunity to learn what kind of riding you like, and what features are important to you.

I think the internet is information overload when deciding on a purchase. Put 1000 miles on any cheap bike, the experience will do more than the internet (or even a local bike shop) to show you what’s important.