Like KenV says, your tool sharpening technique depends entirely on the system you choose to go with.
Some of the pen blank materials need VERY sharp tools, so I'd choose carefully the system that will give you the best results.
I've seen people who can keep their tools nicely sharp using just hand tools-diamond files, stones, etc. I'd be completely incapable of it. I admire them, but I need more help.
Vertical grinding wheels are popular, once you've chosen your wheel, there are a variety of commercial or DIY jigs available. You want to be careful not to overheat your steel which can weaken the temper. A slower speed grinder is safer in this regard. Some fussy turners object to the hollow grind produced by a vertical wheel, I'd avoid 6 inch wheels, but can barely notice it on anything larger.
Belt sanders and horizontal wheels avoid the hollow grind but I can't vouch for how versatile they are for the range of turning tools we use.
Personally, I'm partial to wet grinders because they are safe- the wheel turns slowly, you can touch it without fear, and no sparks. They remove metal slowly, you can't get into trouble quickly and there is no chance of overheating your steel. You must have patience, though because the process can be quite slow, especially when reshaping a tool. The Tormek does a great job and offers a huge selection of well made jigs for just about any tool there is. Other less expensive wet grinders get good reviews too and I believe they are compatable with the Tormek jigs. You still have the hollow grind issue, although the Tormek wheel starting out at nearly 10 inches makes this a nonissue at least for me.
Happy sharpening!