Fail Fail Fail!!!
Fail often! Read a great note from Sketching User Experiences (Bill Buxton) (which I highly recommend for any designer) about a teacher grading half the class on quantity and the other class on quality. During final presentations, the teacher ended up grading the first half based on weight of the pieces, and the other half on the quality of one final piece. In the end, the highest quality projects were form group A because of busily churning out piles of work and learning from their mistakes. Point being, iterate and learn from your prototypes.
We did some laser cutting with Shamilton today from POD. Took several shots, but eventually figured out the right settings for the laser cutter. Not the best example, but a testament to working through your process and learning with each step.