Coming from a programming background, where should I start to learn web design?

I'm a web developer mainly working in front end developing. My main fields are HTML5, CSS3 and Flash ActionScript 3.0.

Here in Iran, teamwork means nothing for most of the people, but I think it's the most important aspect of our work, especially in web design.

I have poor skills in graphic design and UI design. I always have to work with graphic designers for my websites. They are usually good and skilled designers. But they are all print designers and unfortunately they know nothing about the web and designing for it.

For example, one of the designers that I work with most of the time is a great designer and he won a couple awards for his logo and poster designs. However, he knows nothing about the web and most of my time is spent explaining to him how things work on the web, i.e. in what size he should work, using pixels instead of centimeters, and so on... After all he is a print designer, not a web designer. They often think everything is static and constant, not in motion.

So the best way to work around this is to improve my skills in graphical designing. I just want to be able to design good layouts, make good color selections, and etc for my websites. I do not want to design illustrations and do heavy graphical works. Just design websites with no Photoshop illustrations like posters and etc.

What do you do for your graphic works, and if you do them yourself, which books or references do you suggest I read? Where should I start?