I wanted to take a moment to pass on some info that I've found helpful over the years and some others here may as well. For about 5-6 years I've been a subscriber to a blog that's called 'Web Tennis'. It's run by a guy named Brent Abel who is Nationally ranked in a number of age groups and even ranked #1 in the U.S. in several. There is no charge for this blog but about once /week for the last 5-6 years he has sent me an instructional video free via the internet. There is nothing 'earth shattering ' but he does touch on various phases of the game and I've found them helpful to remind me of basic strokes, stratagey, nutrition, etc. Brent does sell various products, video lessons, etc. but it's a very 'soft-sell' aproach. He even tells you that most people that buy things over sites like this never end up using them, so be sure that you will use it if you buy it. In all of the time that I've been subscribed with him I've bought exactly ONE product from him---a video on the serve that helped me a lot with my toss and solved a problem I was having at the time. So, this morning, I've forwarding a video that I got from him for you to take a look at. There are three follow-up videos and I just watched the first one. It was something that I knew but interesting and remindfull of the situation (all three videos pertain to the serve). I'm looking forward to the next two 'lessons'! After the instructional video he offers a comentary column, where you can ask questions or offer your own comments. He answers almost every comment. Often the questions and comments fill out what you just watched in the video.
So, if you're interested, give it a look!