Upwind: The key points are to increase weather helm and create efficient wind flow over sails. Body and helm movements must be super smooth so as not to disturb wind and water flow. It is critical to remain calm, both mentally and physically (this is not easy as you often have to remain in the same position for long periods).
Use mast pre-bend and outhaul to flatten mainsail.
Tighter rig tension will pre-bend the mast (for dinghies) or ease rig tension to power up head sail for racing keelboats.
Have both jib and main luffs eased to create a few horizontal wrinkles, allowing the draft to move aft for better light air sail shapes.
Sheet both main and jib with twist to leeward on leaches to help wind flow.
Be careful not to over sheet the boom. Use the boom well off the centre line in very light breezes and only when sure of your boat speed, attempt to sheet further inboard. Boom down for further drive.
Keep jib slot open and flowing, remember boom is further to leeward than usual.
Rake rudder aft and centreboard maximum forward to increase weather helm feel.
Position crew weight to leeward and forward to create more weather helm and reduce wetted hull surface. Crew should be careful not to disturb wind flow in the slot between the jib and mainsail.
Try to steer by watching wrinkles along the jib luff (on monotypes, the main) allowing them to be slightly back winding for best flow. Try to create correct weather helm feel by careful use of body movement. Don’t allow the helm to go dead by flattening out leeward helm. Try to balance the boat for light airs using rudder and centreboard positioning, rather than having to use too much leeward heel to achieve the desired weather helm feel.
Reaching: The same principles apply as for upwind, i.e. best wind flow by having luff wrinkles slightly backing, combined with good helm feel. For double handed boats the key is your use of the spinnaker and pole height combined with course steered.
You need to position the pole higher when tight reaching as this opens up the spinnaker luff allowing you to point up higher into the wind. If your course is low then your pole height must also be low in order to keep the spinnaker filling. The helmsman must then decide just how low he can afford to steer and still fill the spinnaker. Good communication with the trimmer. The helmsman must be able to subconsciously feel the weight of the spinnaker sheet. The weight decreases to the point of the spinnaker collapsing, then the helmsman must steer a slightly higher course and maintain the balance between good speed and best course to mark. Using the variations in wind speed is critical to fast reaching legs i.e. pointing down in the puffs and up in the lulls.
Running: In very light airs running utilizes the same principles as broad reaching or low course reaches, finding the right combination of boat speed versus best course to mark. As wind increases your gybing angles should become smaller, allowing you to steer more directly downwind.