Four strokes are most easily started by first priming them until they are really wet, usually the carb intake is inacessable for choking with your finger so instead, plug the muffler outlet with your finger while turning the prop to pressurize the fuel tank and force fuel into the carb.

Now that you have the engine primed really wet, make sure the fuel line is full of fuel, no air bubble between the carb and the tank, close the throttle to idle, closing the throttle is very important, connect the glow battery, and then use a chicken stick and flip the engine backwards. This usually gets the engine started. You don't want to flip it through the compression stroke, you only want to bounce the engine against the compression stroke. I usually just grab the spinner and give it a flip backwards. They are extremely easy to start once you have the technique down.

If you use electric starters to start your engines, close the throttle to idle so that the starter isn't fighting so much compression.