Don't run out of gas
I had just got my permit and took the bike I share with my boyfriend out for my first ride in real traffic instead of a parking lot. Exciting and terrifying! He was a newbie too but got his permit and was riding a week or two already. A little shaky at first but then it was great. Intersections were intimidating but I didn't kill it!
Then, I started sputtering on a busy road at rush hour and thought to myself "I really need to get that checked out when I get home!" Then it DIED while driving! I was in the left lane, thankfully just pulling up to a red light, and traffic was all around me. I attempted to start several times with no luck. Ended up having to walk the heavy bike across two lanes of traffic to the right, one of which was filled with cars speeding up to merge on the intersecting road. I pulled it as far to the shoulder as I could but was worried any further and I'd drop it into the deep ditch.
So, I finally got 'er started and was able to pull it up into a parking lot. I called my boyfriend and he informed me that he had just been testing our new bike's fuel capacity! See, we don't have a fuel gauge and we didn't know how many miles we could go before running out of gas! He forgot to tell me he was running it out of gas purposefully and that it might actually die on me in the middle of the road!
My tip is to keep the bike filled up, especially when sharing a bike, and to remember that you have a gas reservoir switch!