To draw a straight line, you first have to choose a brush that's sort of anti-aliased such as circle fuzzy 7X7. Also, you need to sometimes change the spacing between drawn points. A trick that I only found out a few years back is that you can draw a straight line by first clicking where you want to start then hold the shift key and then click where you want the line to end. My favorite trick w.r.t. drawing lines (works with all the other tools such as smudge and eraser tool too).

Straight lines aren't interesting... Any artist will tell you that!

Anyhow, I've been busy tweaking my new installation of Linux Mint. I was trying to get some Windows software to work in Linux without much success. So now I have the all the time in the world to really get my hands dirty with Gimp. I'll keep it simple with line drawings for now and move on to colors and layers later. As soon as I have something that I like I'll post it here in this thread. Btw, my Bamboo tablet is awesome although the active surface is quite small but I'm getting used to it.