1. Make sure your main bridle is the correct length, if it is too short it is a problem. The jib on the jib boom should be relatively tight with a 4 inch slot. It is common for people to use a "racing shackle" i.e. a smaller shackle for racing or even line to attach the jib.
2. Is the jib halyard up all the way?
3. Is the mast tuned?
4. Is the rig tight? Forestay tight?
5. Is the jib wire tight in the sail?
6. Are your battens in the main and jib the correct type?

And then there is sailing.

• It is good to know when to use 2:1 versus 1:1. The sheets should be pulled in enough.
• The jib/main slot between the sails has a happy spacing.
• Look at your wind indicators on the sails, to ensure they are flying happily.