Lets touch base on some pretty generalized concepts.

In lighter air you want to create more draft or shape to your sails, and as the wind increases you want to flatten them out as much as possible.

Your halyard and leech lines are two methods to encourage the sail to cup the wind and increase performance in lighter air.

Keep in mind that minor adjustments make more of an effect on the boat in ligher winds than in heavy weather.

Modern boats with modern rigs result in high aspect sails, with most of your driving power coming from a Genoa. With your headsail you will have several factors to consider when trying to optimize your trim to maximize your speed.

Halyard

Halyard tension is one of the most commonly overlooked control points for your headsail. you ideally want the halyard tight enough to eliminate wrinkles in the luff of the sail but not overly tight.

In light winds you'll get the most performance from a halyard that is just tight enough to remove the wrinkles, and you'll want to increase the halyard tension as the wind increases.

Overly tight halyard tension can actually hurt your performance in light (5-10kn) or moderate (10-15kn) of wind.

Sheet Lead Position

Genoa cars control the sheet lead position for your headsail.

In ligher air you can increase the shape along the foot of the sail by moving the car up as forward as possible.

In moderate wind you'll want the genoa cars around the middle of the track, and in heavy air (15+ kn) youll want to move the cars aft on the tracks to flatten the sail out.

Your leech line is another control line that is easy to overlook.

In light air when you're trying to get the most out of every knot of wind you'll want to build some draft into the leech of your sail but tightening the leech line.

In moderate and heavy conditions you'll want to flatten the leech out by loosening the leech line completely.

This control works best when on a reach or a run, when beating into the wind a flat sail is necessary in order beat into the wind.

Leech Line

The leech line is a great way to help control the shape of your sails.

Generally speaking, you'll want to increase the leech line tension in lighter air and relax the leech line in moderate to heavy air.

By increasing the tension on the leech line you force a cup into the leech of the sail improving performance in light air.

Where as in moderate and heavy air you want to allow some of the wind flowing behind the sail to "spill out".

Be sure to relax the leech line when furling the sail away at the end of your day.

Leaving tension on the leech line when not needed increases the ware along the edge of the sail.

Outhaul

Your outhaul helps control your mainsail just as your sheet leads do for your headsail.

All of the same concepts apply.

Tighter tension in heavy air applications and loosen the outhaul up in light air applications.

For day sailors and cruisers, think of your outhaul as 3 positions (you can apply tape on the boom at these 3 positons to help you quickly find them).

The first position, closest to the mast, would be for light air.

The second position, in the middle of the three, would be for moderate conditions.

The final position, furthest from the mast, would be for heavier air.

Depending on the size of your boat and mainsail these positions could be 2 inches or 6 inches(or more) apart.