For the sake of argument, I will assume that you are talking about a OS 40LA. I remember being so frustrated trying to start that engine that I went out and bought an electric starter for it. Follow the engine manual that came with the engine for starting and breakin instructions. It will tell you where to set the needle valve before starting.

No matter what kind of engine it is, take the plane to your club and ask for help. Tuning and breaking in is not difficult, once you learn how the engine sounds when it is too rich (4 stroke), etc. They can show you how to check for too lean, too rich, etc. I can tell you about the pinch test, but having someone show you is a lot easier.

BTW, my 40LA now starts with 2 flips. I don't even get out my electric starter anymore. If I would have followed my own advice about going to the club, someone would have let me use theirs and I could have put off buying one. Well, advice is usually given from personal experience