Street Bike pondering..

Recently, one of my buddies just got a nice little 600cc Yamaha, (not sure of the model). Nice sporty little bike, very quick (it's a BIKE! of course it's fast) and gets very, excellent gas mileage.

Now, I've first handedly seen a motorcycle crash and it's a horrible site, and we've experienced a death very close to our family at the hands of a motorcycle (no helmet.. RIP Luke), but my loathing of owning and cruising around on a motorcycle, will never, ever die. I've recently grabbed an AutoTrade for bikes (don't even remember what specfically it's called) but it's got a section filled with Crotch rockets, and many for very reasonable prices, something I could afford.

I would want to start out on a small 600cc, or something similar, to learn on atleast, maybe even a bit smaller..

Anyways, where i'm getting at does anybody have any experience riding bikes? I've driven around dirt bikes and four wheelers before, but of course a street bike is slightly different, any tips? Any suggestions?