Now you are ready to turn the pen I usually turn pens at about 2000 rpm, the things to remember when turning are:-
Always use sharp tools and light cuts.
If you stop the blank turning you are either taking too heavy cuts or your tools need sharpening.
Do not hit the bushings with your tools as this will blunt the tools and alter the size of the bushings.
Always leave the blank slightly larger than the bushings to allow for sanding.
The shape you turn it too is entirely up to you but as pens are designed to be used bear in mind the comfort factor.