Here is a great video from Fuzzy Yellow Balls, a site offering free and paid tennis instruction. This video is the first thing you get when you sign up for their newsletter, which I recommend you do.
What I like about this video is that it describes something that I teach as well – the fact that, even though there are different styles, there are certain fundamentals which will always be there in a world class stroke. This video details 5 of those fundamentals for the forehand.
Enjoy!