Poor speed
If boatspeed seems poor, you may need to add power. Try deeper sail shapes, and bear off a couple degrees.
You can also be slow from being overpowered, in which case you’ll also have too much heel and lots of weather helm. Reduce power and balance the helm to restore speed.
A fouled bottom can also have a big impact on speed.
Poor pointing
If your boatspeed is good, but the boat is pointing poorly, try sheeting harder. Trim the jib until you get a hint of backwinding in the main, and trim the main to the verge of stalling the top leech telltale.
Too much weather helm
Reduce heel to reduce weather helm. Try flatter sails, and more twist. Also, feather up to reduce angle of attack.
Weather helm may also be solved by better balance between main and jib: too much power in the main, and not enough in the jib. Add power to the jib, and/or ease the main.
If weather helm is a constant problem, try tuning your rig with less rake.
Jib telltales hard to read
If both inside and outside jib telltales are constantly dancing, create a wider entry angle and more forgiving steering groove by easing the sheet and/or tightening the halyard. With the draft properly positioned, the telltales will settle down.
Too little weather helm
If you have no feel in the helm, add power. Try deeper sails, and bear off a few degrees. Also try moving weight to leeward to increase heel. In light air, a lifeless helm may be a sign of being overtrimmed. Ease both sheets, and bear off to add power and speed.
If a lack of helm is a consistent problem, consider retuning your rig with more rake.
Pounding and pitching in waves
Sailing into waves requires power to punch through the waves. If the boat is pounding, then foot (fall off) slightly and add twist to keep from being overpowered. Also, moving weight (like anchors) off the bow and out of the forepeak can significantly reduce pitching.
Overworked Autopilot
If your autopilot is constantly searching, and can’t seem to settle on course, and your boat is upright and underpowered one moment, and overpowered the next… add twist. Twist creates a more gradual onset and release of power.
If your autopilot is working too hard, retrim for better balance. Add twist to smooth out the transition from overpowered to underpowered.
Also, if you have the option, set your autopilot to sail to the apparent wind angle when sailing upwind, rather than your compass course.
Overpowered
A small jib and reefed main provide a balanced rig for best performance in heavy air conditions. For more details, read Heavy Weather Sailing Techniques.