A tactic I like is a short angle slice off the forehand, one that lands near the side line around the service line. The ball stays low, so it's hard for them to returnt a winner. Even better, the other player is out of position, AND has to make fast decisions. I've got an entire open court they have to defend. That means they have to move fast, and are vulnerable to my hitting behind them when they move. Also, they have to decide whether they come to net or go back.
Their only chance at a winner is to return short angle, but I've still got that open court, and a short angle return leads me right to an up the line winner off my forehand. The beauty of it is, everyone knows I do that, and they can't do anything about it except run. At worst, it grinds them down.
Also, most of us are not as fast as Serena. So if I'm at the service line, even a mediocre drop shot, followed by a lob, is really effective. And it annoys the hell out of net-rushers.
Proud to be an American
Not blind. Not uninformed. We are party to atrocities. But the response of the world after 9/11 is worth noting. Even our most dire enemies offered aid. We should all be so lucky.