I've always been mystified by those that pay big bucks to have their guns stippled. If you have a reasonably steady hand and can spare $15 for tools, you'll have all you need for a lifetime of stippling. I've given a pictorial below of the method I use to stipple my guns, hope it helps.
The Girsan grips in their all their stock grossness.
Here's my trusty "stippler". I picked this sweet baby up from Princess Auto for $10. It's a soldering iron and came with a bunch of little nubs. I wasn't happy with those and after some trial and error, decided that a larger melt makes for a better grip. I filed down the pinpoint tip to the dimension you see here.
Everything you need to stipple your gat is pictured below; sandpaper and soldering iron (the shoe polish isn't needed, I just couldn't find the holder for the soldering iron and didn't want to burn my workbench) - that's it! I use a very coarse sandpaper to remove the high points and lines from my grips. If you don't, you'll likely still see a faint outline of them after you stipple. It's purely an aesthetics thing, but it only ads about three minutes to the whole process.
I like to start slow and work my way around the edges of the grips (or frame). Make sure you have your soldering iron good and hot before you start stipplin'. You only need to press it lightly to the plastic for a fraction of a second. Go slow and light at first and you'll get the hang of it.
After I make my initial row of stipples around the edge of my grip I like to random stipple the middle and around any faint outlines I didn't take off with the sandpaper. If I don't do that I have a tendency to stipple around the lines and designs and it doesn't look as random as it should.
Then I just fill in the non stippled parts. You can get as OCD with this as you like. I prefer a more random look. I'm sure the fumes of melting plastic are probably pretty toxic, so if you can, work in an open space with a fan pointed at your work to blow the fumes away from you. Mask up if it's important to ya.
One down and one to go.
Finished product! It only took about 30 minutes to do both grips. The gun sticks like glue now. The Wilson parts are the HEAT by the way. They dropped in just fine, and work as advertised.