In tennis, as with most sports, footwork is paramount.
In tennis the basic element of footwork is called the split step. If you've ever watched me prepare to receive serve, then you know what it looks like. If you've watched some of the veteran players prepare to hit a groundstroke, you may also know.
The split step is the basic building block of all footwork in tennis. You can't play effective tennis without it. Period.
And here's the best part. You don't need me to to explain it or teach it, though I'd be happy to oblige. Videos are all over the Internet. I'm suggesting this one, but you can take your choice. Even better, you can practice at home. Even in your house (though I'd recommend outside to prevent vases from falling off shelves.)
Mastering the split step, i.e., making it an integral part of every point you play, will make you faster and keep you more mentally involved. Seriously.
So watch the video, or look up the term, or ask somebody, but make the split step part of your game. You'll be amazed at the results.