There are some around here who think that a 600 is fine to learn on. (I'm conflicted on it..)
The most important thing to know is that that bike will be touchy.. in every way. It will respond to your inputs very quickly.
Take it real slow. Figure out the throttle and braking of it, without putting yourself in weird handling related situations. Once you have the throttle response and braking relatively mastered, move on to figuring out the handling (i.e. geometry) of the bike.
If possible, figure out these two things seperately. What I mean is, don't put yourself in a situation where you're new to it, and you have to figure out how to control the throttle and the handling at the same time. Take it one dimension at a time.
Maybe a parking lot is best for this, or maybe your nearest residential roads with 25 mph limits.
Just take it all slowly. Learn one thing at a time and don't try to put them all together too quickly.
The most important thing to know for a person in your position is that the bike will respond to your inputs faster than you can figure out how to make them.