Its not a bad idea to find a large empty car park and spend some time just slowly riding around it getting the feel of your bike, practicing your take-off's and getting your balance. Even with over 40 years of riding all sorts of bikes one of the first things I do after getting a new bike or on one I'm not used to is ride around in a car park.

 

Some really good advice on here. Also remember the bike goes where you are looking. Target fixation will get you tangled up REAL quick.
Expect every car to do the worst possible move you could imagine them doing (turning w/out blinker, pulling out, cutting you off). If I see someone coming towards me and they put their blinker on for a left turn, I just assume they are going cut me off. Then the 20-30% that it happens I'm expecting it.
Also remember the most important thing, to have fun!

 

Its always fun riding with others but remember to not try to push
your self to do things your not confident doing. Being semi new to riding on the street myself when your with other people who may be more experienced than you, you might start playing keep up which make you riding faster or harder than you should. Comfort and skill comes with time.