Step 1: Choosing a raquet
When looking to buy a raquet, you should figure out the level of play you are at.
Beginners might want to choose a head that is wider, which reduces the chance of missing the ball. More experienced players might want to choose a more narrow head which has more power and accuracy.
Did you make this instructable?
Yea a great overview of how to play tennis, I think a extra page on tactics and strategies for beginners to advanced would have been nice.
It always good to mention how to set up the points with your strengths and the serve combinations to predict where the ball is coming. Serve combination is also a great way to deal with
pressure as you have a set plan ready. (Serve out wide, the return will go cross court 75% of the time, to your forehand) So you can be ready for that! Along with other tactics such as always hitting down the line when you come into the net so as not to give your opponent angles for a passing shot. Here's a sampler at http://www.how-2-tennis.com
As Flea rightly mentioned as well, the footwork is another vital element! But I wouldn't say the open stance is always best. In todays game you need both. The closed for approach shots (as it disguises where your hitting, and allows you to move up to the ball quicker) and the open for baseline (as you recover laterally quicker)
Either way great information!