So, I recently had this avatar done for me (check my sig for artist's dA page), and it made me think about how important a skill like drawing is.

So I want to improve my artistic skills. But I really svck at this, especially with proportions, and I don't know whether I'm even capable of drawing on a computer program; for some reason, I can't draw a straight line with a mouse.

What is the best way for improving this skill?

Go draw some more things.

Practice is the best way to improve any skill. There are plenty of books out there to help, and proportion is one of the more tricky aspects of art, i think. You can also start paying close attention to the work of others, to see how they manage it. But in the end, draw, draw, draw.

Thanks. Any tips on speeding the process up?

Can artistic talent be taught? I don't know of any people that can draw good who haven't been drawing all their life and improving upon their natural talent.

As for drawing with a mouse, I'm horrible at that as it feels so foreign even though I can draw well with pencil and use a mouse almost every day. Also there's techniques to drawing/painting that only a pencil and brush can properly achieve, programs mimic those effects but it's not quite the same

Like all skills that need to be learned, practice and commitment are your best friends. The more you practice, the more you learn how to expand and apply your skill.

Art isn't something that you should want to "speed through," it's more something that you learn, study, and contemplate. Having patience will reward with a better understanding of the process, and of your own artistic ingenuity.

I would not recommend learning with a mouse. A stylus and graphics tablet are much easier, and feel more like the traditional pen & paper.