I have asked so many questions recently, and everyone has been very helpful to answer. So I just quick wrote up some tips I concentrate on. These are some really good drills and tips I can give you (after swimming competitively for over 10 years :) ):

Focus on reaching as far forward as possible. You want to grab as much water as you can, because this will give you a much more efficient stroke. A drill you can do to practice is the six-kick drill. Six kicks on one side, then take a stroke and rotate fully onto the other side. Six kicks, stroke, and onto your other side, repeat.

Your hand should also enter the water far in front of you. If you are reaching far enough, you will notice you are rolling your shoulders to get that extra reach. Your hips should naturally roll at the same time, otherwise you will look like a snake through the water.

Don't cross over. Pretend there is an invisible wall down the center of your body. Don't let your hand hit or cross that wall while you are pulling.

Hand entry. Your hand should enter the water smoothly. You can tell because if there are a lot of bubbles in front of you when your hand enters, you are slapping too much. On the other side of the spectrum, don't enter your hand with your thumb down. You need to catch the water, yet make it efficient. Any splashing is simply wasted energy.

When you are pulling, make sure you pull ALL THE WAY. Don't short yourself and take your arm out of the water too soon. Again, this will give you a more efficient stroke. Pull all the way down, and visualize where your hand is before you take it out of the water.

When you are pulling through the water, make sure your arm is NOT fully extended. Your hand should be pulling through close to your body, yet comfortably. Try pushing down on something with your arm straight out in front of you. Now push down with your arm slightly bent and your hand closer to you. You will see MUCH more power.

Don't waste too much energy kicking. I barely kick at all. Simply kick light enough for your legs to stay near the surface of the water, so they don't drop down and create drag.

Minimize the path your hand travels through the air. Don't waste time and energy swinging your arm. To practice this do the fingertip drag drill. Simply drag your fingertips right through the surface of the water.

Breathing. You only need to take one goggle lense out of the water to breath. Any more than that and you are wasting time. Also make sure you are always breathing air out, or taking a breath. Don't hold your breath during your stroke and then breath it out all of the sudden before you take a breath. This can make your stroke less smooth by requiring you to take longer breaths.

Some people breath every three strokes, and swear by it. I, however, just breath every other stroke (always on my right side). Just be careful because in the open water this can cause you to swim in a curved line rather than straight. I also like getting the air more often :)

Stroke count drills. I naturally have about 14 strokes per 25 yards, but to create a more efficient stroke do intervals where you work on swimming 1 - 2 strokes less than normal per 25.

That's about all I can think of off the top of my head for now...If I think of any more I'll add it on.