I've tried all sorts of tricks of writing on tape, writing on water slide transfer paper, but writing directly on the blank works best for me. I use a Rapidograph pen with opaque white ink. It's kind of like a traditional quill pen, but a little easier to use, in my opinion. If I make a mistake, I erase using a natural brown coffee filter (lint free) and rubbing alcohol. Once I get it perfect, I dab on clear color preserver (the white water-based stuff leaves just a slight halo when you hold the finished product to the sun). Dab it on so that you don't smear the ink. Once that's dry, epoxy as usual.
Those are my tricks, but I'm sure you'll get other opinions as well.
I've used the Gel Pens before. The nice thing is you can get them in a wide selection of colors. Make sure you give it plenty of time to dry, then apply a coat of color preserver over it, being careful not to get the brush on the inscription. Another trick is to use a light coat of the varnish in a spray can.
Like Wes said, I like to write on the blank with a gel pen, apply some spray fixative (available at Michaels) or even hair spray. Let it dry then drip/flow on some polyurethane. Let that dry completely and flow on a second coat for good measure. After the second coat you can do whatever you want to it.