The good kind of spin - backspin - comes from hitting the ball cleanly, then making a divot after impact.
Players who win on a clay surface are those who can control the ball, playing steadily and accurately from the back-court, keeping the ball in play and moving it around with changes of speed and spin, and resisting the temptation to over-hit.
The one-handed backhand helps you to be more aggressive in the points.
The key is to hit the ball first, then the sand. Even if you catch it a bit thin, you'll still get plenty of run. Hitting it fat is what you want to avoid.
I grip very close to the butt of the racket. This allows me to get a lot of wrist action to create more spin and whip.
On clay, you know that you have much longer rallies, and you must run for maybe two or three hours.
On clay courts I have some weapons to play a good match.
It's tough to control the ball on the clay.
