i had a 89 Honda HawkGT 650 Vtwin. its the CRX of honda bikes, no kidding. small, highly modable, cult following on the internet (and oddly in San Francisco), great race bike, fun but underpowered street bike, great handling... and sold in the US from 88-91.
i sold it last year because i just didnt ride it anymore. no time, no interest, no need. i put about 20,000 miles on it myself and worked and maintained it myself.
anyway, my advice starts with: take the MSF course.
i repeat: TAKE THE MSF COURSE.
learning to ride a bike is very counter intuitive. its like learning to snowboard, the body wants to do different things that works against proper control of the snowboard/bike. such as leaning INTO the turn, not leaning away. also looking where you want to go, not right in front of you where you think the worst danger is. you go where you look. anyway, lots of other things they will teach you that you simply wont learn on your own, at least safely and properly.
the side benefit is that it makes getting your motorcycle license easier.
i honestly dont recommend starting off with a 250cc as your first bike. i believr that there are things that you will need to RELEARN to control a 600cc bike that you probably didnt have to deal with a 250cc bike. the wieght, the speed the whole feel of the bike is too different. so its my opinion that getting a 250cc bike is a waste of time. get an old, used 600cc CBR f2/f3 or something that already lost its value and wont lose much else if its resold.
also, i would feel naked riding without my jacket. and i would rather spend money on a decent, but cheap helmet and make sure i buy a decent leather jacket and gloves than putting all my money in a fancy/expensive helmet and ride around in just a t shirt, despite the hot socal weather.