Judge your mast rake by the distance between the mainsheet blocks and the boom blocks when fully sheeted. You should be touching or nearly touching the blocks together. This works as a guide regardless of the type of blocks you have. The idea is to get as much rake as possible to point highest.
Add tell tails to the sail leach at about 3/4 way up. These should indicate whether you are sheeted correctly. Try to have the tell tails alternate between flowing aft and hooking around the leach. If they flow aft at all times, you are under sheeted. If they hook around to the leeward side at all times, you are over sheeted. Biggest mistake is to over sheet and stall. Allow the boat to attain boat speed before coming up closer to the wind. Coming up too high too soon can also stall the boat.
There are a few tips shown in our support section. One is a telltail placement suggestion. This one shows tell tails over hanging the leach. Many people put them right on the leach edge:
Check the jib sheet tension and tack hole attachment point. Adjust the tack attachment to open up the "slot" between the main and jib. The jib leach should have a similar curve as the main luff where they overlap.