Is the feel of your USB tablet not quite right? Customize it! This video takes a look into the way Wacom tablets function in an attempt to make them feel more comfortable to draw on. If you missed the previous videos, you might want to watch the ones on Stylus grip and Stylus "Tip Feel".
Why are console video games played with a controller or a touch screen, and not a keyboard? Because those are the best-suited input devices for the way most users interact with their device. Guess what? Being a digital painter means you're no longer included in "most users". Now you've got a different set of needs, and will most likely be spending longer at your computer than the average user. With this in mind, a standard keyboard might not be the best input device for you. Just like using a stylus instead of a mouse, you might want to consider alternative keyboards or controllers for your other hand.
When it comes to ergonomics, re-mapping your keyboard shortcuts is a great start - but it doesn't need to be the end. Over the years I've radically changed my input scheme and the results have been very clear: expensive, but worth every penny.