If you can post some photos we can probably help you more, but I rig mine with enough downhaul until the battens are close to the mast and the leech is quite floppy, then I put on minimal outhaul usually only 1-2 cm. If the wind is low then I put on 0 outhaul. I always try to have the battens so that they arent pushing forward against the sail as this damages the sail.
If you have creases in the sail you might need to change the batten tension, sometime creases can happen if one of the battens has more or less tension than the others.
I agree with what Al says; but I probably don't use quite so much downhaul and tune more on the outhaul. Check the link to the rigging guide for some tips: [www.severnesails.com]. Photos are also useful.
Also make sure you are using a mast that is compatible with the sails.
The sail may crease a little if it is rigged quite powerfully when twisting off under load. This is'nt too much to worry about.