I'm a terrible designer too, so I'm really not in any position to give advice, but I can share my process. I figure, like any other technique, the way to get better is to do it a lot. I usually get so frustrated after trying to make a decent design for one website that I don't do it again for several weeks. Anyways:
0) learn new design techniques. Try to do this regularly. Its like adding new tools to your toolbox. A list Apart has a bunch of great tutorials, and checking out design galleries (http://html5gallery.com/ has some nice sites) helps to give you inspiration and give you something to try to duplicate on your own. I don't mean to duplicate good designs for your own work, but to duplicate good design so you can learn the techniques used.
1) Sketch a design on paper. I don't focus on making it look cool or pretty because I don't know how. I try to focus on solving the user's problems. I do several sketches, and ask friends to glance at each. At the very least to see if they get the idea of the website from looking at, but also to know which ones they like best.
2) Graphical Mockups. I use the gimp or adobe fireworks. Again, I make several different mockups from my best sketches (between 2-4). And again, I have friends and colleagues review them and get their feedback. I put as much detail as I can into each - hover effects, shading, et cetera. I try to make a pixel-for-pixel mockup of what the actual html/css will look like.
0) learn new design techniques. Try to do this regularly. Its like adding new tools to your toolbox. A list Apart has a bunch of great tutorials, and checking out design galleries (http://html5gallery.com/ has some nice sites) helps to give you inspiration and give you something to try to duplicate on your own. I don't mean to duplicate good designs for your own work, but to duplicate good design so you can learn the techniques used.
1) Sketch a design on paper. I don't focus on making it look cool or pretty because I don't know how. I try to focus on solving the user's problems. I do several sketches, and ask friends to glance at each. At the very least to see if they get the idea of the website from looking at, but also to know which ones they like best.
2) Graphical Mockups. I use the gimp or adobe fireworks. Again, I make several different mockups from my best sketches (between 2-4). And again, I have friends and colleagues review them and get their feedback. I put as much detail as I can into each - hover effects, shading, et cetera. I try to make a pixel-for-pixel mockup of what the actual html/css will look like.
3) Finally write the html/css for my best design.