The prop placement is most important. Take a G-62 for instance. The instructions say to put the prop across the two cutouts in the hub.
This puts it so that with the prop in the 9:00/3:00 position (straight across) the magnets in the flywheel are just starting to come up to the magneto pickup. This is not top dead center and you will not feel compression like you will in a two stroke engine. I prime my engines with a prime bottle just like a two stroke, saves a lot of time choking the carb and drawing in enough fuel. Gas engines like to be wet to start and sometimes it's hard to get them wet enough without priming. I open the throttle fully and squirt in a good prime. Turn the engine over slowly a couple of times to distribute the prime. Close the throttle to about 1/3 and grab the prop at the 3:00 position, I rock it back slightly and throw it through compression. You will not feel the compression coming up like a two stroke. I think this is where most people have trouble with starting a gas engine. They bring the prop up to compression and then flip it. By then the magnets have already gone past the magneto, NO SPARK. Usually within 3 flips the engine is up and running, it depends on the amount of prime. It literally is all in the wrist. The secret is in the position of the prop. If you don't have it set right you'll wear your arm out and not get a pop from the engine.

Larry