First we used this piece of classroom equipment (click link for description)
I find it's great to start the little ones off on this since it has a large knob for grasping, and the tracks to trace are large, so the knob flows easily. There is little frustration with this equipment and the children are drawn to it with out prompting.
We also do tracing in sand and recently I found these cards which helps direct our process. The kids really enjoy this activity.
Then of course we practise with pencil and paper - we added sponge grips to make it easier.
In all of these activities we find out hand dominance - what type of grip the children are using - who needs help with grip - what level the children are at in the preprinting process, and what activities we need to add or take out of the process at the time preprinting activities are introduced.
The children fully participate in all of the activities introduced without proding - they find great pride in the success they achieve with practice.