For almost any workout I always do a good number of shoulder pass throughs with a PVC. The important thing here is to always try to work your hands inwards as time goes on (from session to session) so long as you maintain proper grip and get the right motion. Simple video showing some pass throughs
[youtube]http://www.youtube.com/watch?v=rFhMoRNrSKs[/youtube]
whenever we are going to do cleans or front squat we also like to do some wrist/forearm stretches before we start. You sit on the floor and place your palms down, fingers facing you

Lean back while maintaining your entire hand on the floor. Should feel a good stretch in the wrist and the forearm.
Now, the other wrist stretch is to put the tops of your hands on the ground and do the same stretch as shown above. This will hit the tops of your wrists and forearm. Be easy on this one, go into it slowly and apply force gently. It can be a little awkward.
Now there are also some barbell stretches and drills you can hit as well. This one is a little hard to explain so tonight if I can I will take a photo using my own barbell.
Put a barbell in the rack. Put your hands on the barbell with your front squat grip width. While here you need to walk under the barbell and put the barbell on your back rack but with your front squat grip. Its kind of hard to explain in words, much easier with a picture.
Walk off the rack and now from this position try to drive your elbows up as far as you possibly can. If you cant drive the bottoms of your triceps up to like 33 degrees off your shoulders then you need to work on this. Should help to develop flexibility in the front rack position. I will shoot a photo of this to show you how it should look.
Now if you have a partner around or someone who is okay being close you can do a partner stretch for the front rack. Basically you get in the front rack with a barbell (no weight needed) then have your brokski face you and push up on your elbows (bar can be racked still while your in the position). Find a good amount of torque so that you can feel it stretching you out a bit.
Vid suggested this video
[youtube]http://www.youtube.com/watch?v=dGfR-qD7V-Y[/youtube]
The same kind of idea as what I have suggested