Some things I know:
-Not all kits are equal! If you shirk, and get an entry level kit, you're going to get an entry level sound, that may even push you away from the drums....
-Don't underestimate used kits. They can be a great way to get a good kit for cheap, and even get some real cymbals to come with it (you'll want to buy the kit with
Sabian,
Zildjian, or
Paiste, probably.) Unfortunately, you have to be careful. You could get a piece of crap, and you can't really test them. I suggest going to a store after you've fouhd a deal you like on the internet, and trying out that kit before you reply to the ad. It's an easier way to ballpark how it'll sound.
-DO YOUR RESEARCH! I myself tried to learn as much as possible before even looking for kits, and now I'm SO GLAD I did! I even got a relatively cheap kit (quality cheap), but with the right heads, and knowledge on tuning, they actually sound great. Better than $1200 kits at my school. Price does not always equal quality, when you're buying used. Also, pay attention to the cymbals with the kit. I didn't do that, and I regret it. It came with
Sabian B8s, and I've replaced them all with AAs, New Beats, and Xs20s.
-You're not going to know everything. I STILL don't know my wood preference, or my company preference. And I'm a strong believer in WHO CARES? Obviously the wood makes a difference (maple=higher pitch, ash=medium, birch=lower pitch, I believe), but as far as companies go, it doesn't really matter unless you're getting an endorsement deal! You can even go for Franken-kits, where every drum is a different company

gotta love it.
-Older kit= Older hardware. Remember that especially. I bought a prehistoric kit, and the bass pedal and high hat stand broke as I was playing them. That being said, it's not always bad.
In conclusion, I like to buy used USUALLY, but it's not for everyone. The real thing to think of is "Do I need this to be new?" For example, I buy mic cables, condoms, and drum sticks new, because that's not something you want someone else using before you

you never know how hard they hit
Just remember that it's ultimately your call, so just play as many kits as you can to get an idea of what you like. You will not regret it!