Fred,
I have had a great time with the polymer clay, and I am sure that you will too. I have a few newer polymer clay pens in my album. I don't have a lot of advice for you, but here is what I will say:
1- Experiment and have fun with small batches. Try some new ideas.
2- Plan on using any packet that you open right away. If you are going to do a 7 color pen, you had better be prepared to make at least 14 blanks. (one 2 oz square makes a minimum of 2 large style pens)
3- If you buy from Michael's, they always have a 40% off 1 item coupon in the paper. You can buy some cheap multi packs this way.
4- Most problems (tear out, chipping) occur when using the penmill. I found that squaring the ends with the sander worked best, or just making sure that the ends were square before baking by putting the bushings on before baking.
Have a good time and post some pics when you are done.
Cheers,
Mike