The first flight of each flying session should start the same way.

Start the engine with the trottle just barely cracked open.
When it starts, let it run at that setting while you put aside the starter and kit and until you've moved behind the model. That should warm it up some.
Open the throttle and let it run a moment.
Slowly open the needle valve until you are sure that the engine rpms are slowing. The mixture is rich for sure, and the needle adjustment is starting from an absolutely safe adjustment.
Slowly close the needle valve until the engine reaches it's max rpm.
You will know it's at max when it starts to slow down from being too lean. Immediately upon hearing the slow-down, back the needle out 3-4 clicks.
Now the needle setting is still too lean to fly for most engines. You're at or near max rpm on the ground, but the engine unloads in the air and this setting will not provide enough fuel in the air.
If you see no exhaust smoke, the needle is definitely too lean for flight.
Richen a couple of clicks and fly.
Now comes the important part. If you do not see exhaust smoke in flight, land right away and adjust the needle out a couple of clicks and look for exhaust in flight again.

You're not done yet.
Remember how many clicks out from max rpm you've put on the needle adjustment in order to get a good setting for flight. After a few outings, you'll have a good idea how many clicks rich to take the engine during that first needle adjustment of the session.

It takes longer to type than it does to do it. And it's really simple and easy to do.