First of all build the clutch like described in the manual, so with the advised preload, gap and endplay.
Then try the car on the track, if you feel the car lacks acceleration the clutch engages too soon and you need to tighten it. Start tightening it until you hear it slipping on the track. It's slipping when the engine revs rise fast but the car doesn't accelerate as fast. When it starts to slip loosen the preload nut by a quarter turn and you have a good working clutch.
When you have your preload set accordingly you can try different gap settings and fine tune the preload tension for those gap settings. When you increase the gap you normally need to loosen the preload nut a bit and when you decrease the gap you can tighten the preload nut a bit.
If you're still experiencing issues ask an experienced club member to help you out.
Personally I either run a .45 gap or a .50 gap and adjust the spring tension like described above. This is with a Capricorn clutch.
In the download section of my website you can find a manual on how to build a Capricorn clutch: