These are pretty simple as motors go. That's not to say they won't have you scratching your head from time to time.
First thing is to check for fuel. Remove the plug, if it is wet, you have fuel. While the plug is out, check for spark by grounding it to the head and turn the motor over. If no spark, first thing to check is the kill switch. Don't be tempted to run it without a way to shut it down if the throttle sticks wide open.
That is really about it. If you have both spark and fuel and it still won't start, you are either getting too much fuel or not enough fuel. Then, with spark is it happening at the correct time and with enough intensity?