If you have never done this under sail, go to the library and get Chapman's or a similar book and know the diagrams for landing and launching under various conditions.
Most important things is to know your boat and the the the launching area. The most important thing to do is use the wind. The most important thing to have is an altenate plan when the primary plan gets blocked. In everything you do, know what the wind will do to your boat. I never launch the boat even from a familiar dock or beach without walking the dock and beach observing the wind and water in the area before the boat is in the launch area.
In launching, you want the wind pushing you away from the dock so make that the most important thing in your launch plan. If possible when launching without a dock let the wind move the boat down to the beach from which you will be leaving.
When leaving the dock, place your boat in the best position to use the wind. launch from the end of the dock, rotating the boat if necessary. consider the docklines as part of your steering system, when leaving let the boat pivot on the stern line to get the bow in the direction away from the dock. If forced to leave from between boats, allow the wind to push your boat from the dock using the bow, stern and spring lines to move the boat from between the boats, and then release them in the order that will allow you to sail from the dock. Do not be afraid to get the lines wet, loop them around the dock fitting and when released pull them into the boat.
In some condition you can actually back the boat using the sails, (That really impresses the bystanders). We use to launch from a ramp that was in a narrow cove, Because of the shape of the shore and when the the wind was directly off the ramp it was easier to move the boat to the outer end of the dock and sail backwards a couple of hundred feet then bring the bow around and sail away.
In the worse conditions make sure the boom and sheets do not tangle the dock fittings, both coming in and leaving
Plan your landing, make a couple of passes of the area to identify all of the boats, the wind conditions, and the conditions at the dock.
Don't be afraid to make multiple short tacks to get into the best approach position. Watch out for the guy with the motor who slowly backs his boat out of the place he thinks you are going, into the the position you must be on your next tack that you must make because of the wind, shore, the dock and other boats.
The stronger the wind the more likely the final distance is with the sails down. Usually I leave the dock with the main and jib sails set, but hanging free, as a with a motor, you keep the sails idling, and be ready to respond when you push on the throttle. In some conditions the extra draw from the jib without the main may be the difference between hitting the sand bar that you did not know was there and become stuck.
Make sure the crew knows exactly what you plan before your are in your final positioning in the launch area.
This is what makes sailing an athletic sport When you are walking to get the car, you can sneer at the motor boaters who had bets that you would not make it without hitting their boat. Or hear the bystanders conversation where one tells the other see I told you he did not have a motor.
