keep the serves wide!
.......ive played only doubles on clay before. like everyone else suggests, keep the spin heavy, play the percentages, and move your opponent around. in terms of doubles, be sure to keep the serves out wide as much as possible to really open up the court for your partner to have a chance at a putaway off the return. up the line serves are not nearly as effective unless you can either pound the crap out of them with minimal effort, or give it a wild kick to emphasize the surface.
one more thing is to really use the heavy topspin lob to the best of your ability, considering even if they can get their racquet on a low/accident the clay will slow it down enough for another return or catch them off gaurd off from the last shot.