I had a simliar problem the first day I road my bike.

A few things I found, The others have said it too. I tightened down the connections after cleaning them on the battery. Don't use a screw driver, make sure you use a wrench.

another possibility, make sure your kickstand kill switch is functioning right. I noticed sometimes it would slip down and kill the engine. Did not realize this until after I solved all my other problems.

Lastly, i had really dirty gas tank. Alot of crap at the bottom. It died mostly when I let off the throttle after higher speeds. After about 10 seconds it started up. So I think something was clogging up the carb jets. I ran a bottle of seafoam and that helped.

Hope this helps a tad. Still a newbie but people here are very helpful and just giving back from something I experienced that is simliar.