Just a note on new engines or any that haven't been run in a long time. What I've been doing my whole life is to remove the plug and simply squirt a bit of fuel into the cylinder. Only needs a small squirt. It'll fire right up for sure, and 9 times out of 10, it will run for 5-10 seconds which is long enough to draw fuel into the carb and continue running without stopping! If it stops do it one more time.

This method is MUCH easier than nearly every other method I've seen and or tried.