Came into this thread to recommend this book and upvoted here.
This is an older book, the 3rd edition is from 2008, but the first edition is a few years older I think. The most surprising thing (for me) was that design principles have not changed much in the past 100 years or so. This book is geared more towards print design (newsletters, fliers, business cards, etc) but the concepts translate really well to the web.
Another point is TYPOGRAPHY! This shouldn't be overlooked and is easily the best way to improve the design of your site. Color schemes, graphics, and ornaments are secondary to getting the typography (font choice and style, layout, colors, pairing, etc.). Please do yourself a favor and read this article from the world-renowned web designers at Information Architects: http://informationarchitects.jp/the-web-is-all-about-typogra... -- be sure to read the resources at the end of that article. It's s a great place to get started.
3. Using wordpress as a frontend for your website (even if you don't have a weblog) allows you to swap in one of thousands of fantastic themes.
Whenever a friend asks me to put together a website, I just ask him/her to pick a theme, and host wordpress with static pages. It's a lot more easier to maintain and has more choices as far as visual content is concerned.
Excellent suggestion. Although I think design is a skill that has to be learned by practice (and there's of course natural talent involved), Non-Designer's Design Book gives you a few concepts that allow you to better understand why some designs just look better and some don't.
One of the biggest tool for me was that you shouldn't be wimpy, but make big contrasts: e.g. select large font & small font instead of two that are too close to each other.