Surprisingly, none of the above very helpful answers has mentioned the simplest aid for you.
You will notice a small clear window in the sail, with red and green streamers. These (called telltails) are an extremely accurate instrument (seriously) designed to help you.
All you have to do is place the sail in the wind so both red and green telltails fly horizontally.
There are two slightly different situations. Going towards the wind.. and not lol
1. Going towards the wind.
As per the diagram above, you can't sail directly into the wind, so sail at about 40 degrees either side of the direction the wind is coming from. Tighten the mainsheet until the sail is pretty close to your head. Now see if you can keep those telltails streaming. Here is the "secret"! Steer the nose of your Island AWAY from the telltail which is not flowing (subtlety here, make small changes in direction). No doubt, you will start out zigzagging as you move past the perfect direction, but with practice, you will get "in the groove, where both telltails sit there like they are glued to the sail. DONE!
2. Pointing in any other direction.
Steer where you want to go, and then pull the mainsheet in or let it out until you get those pesky telltails streaming again. In this case, pull the sheet in if the telltail facing you isn't flowing; let it out if the one behind the sail isn't flowing. Again, make subtle adjustments.. you will soon get the hang of it.
That's it! You are now able to sail efficiently!
Now the last bit. Once you have the above under your belt, watch the lower (or leeward) aka, and adjust the furling of the sail by keeping that aka from being driven underwater. Having about 2 inches of aka above water on average is what you aim for.
Go out and enjoy yourself!