I'm no chess master, but I'd say I'm about average for the little I play. Usually I make about two to four moves just to get my defenses set up as well as plot a course for the King.

I always try to keep the King as my primary focus and then work backwards from there. I look and see how my opponent has moved and look for the possible checkmate spots. Judging by the defenses and keeping in mind which ones are currently unusable/usable and which ones my opponent will likely free up, I plot a multi-directional course. When you move a piece, know at least two or three moves ahead how that piece could be taken and how you can depend upon that.

Also, don't be afraid to sacrifice certain pieces, especially if you know that you can get them back. If you're playing someone in real life, it can be very helpful if you have something set up to try and get your opponent to focus on that piece. Make it seem important.

Don't let your opponent get himself into a stalemate position. If I'm obviously going to lose, the first thing that goes into my head is a plan on how to stalemate the board. That's another useful thing to learn sometimes, but it annoys the heck out of the aggressor!