Here's what I did to start solving this problem: I hired a good designer friend to have weekly design sessions with me.
They've been incredibly helpful, and a lot of fun. Books and blog posts help, but nothing beats having a passionate teacher sit next to you and coach you along.
Here are some recommendations and details on how these go down, if you're interested:
1) Read 1-2 books on design beforehand (I recommend these [1]), perhaps introductory in nature. There are several principles and beginner concepts that you can become familiar with on your own that'll provide a better foundation once you've hired a design tutor or coach.
2) Have a tangible goal to facilitate your learning. Like any art, everything design related takes time, and having something interesting to retain your focus over days, if not weeks, if not months, will keep it fun and meaningful. My tangible goal has been redesigning one of my company's products.
3) Before each session I send my designer a page or two I want to focus on (e.g. client list and client edit pages), goals and sample content, and examples of designs I like for inspiration. We both work on designing those pages independently. We don't share or view each other's work until we're in session.
4) Once we're in session we review our designs and discuss each of our decisions on spacing, content choice, emphasizing this or that via different font styling, coloring, etc. As expected, my designer's work is always superior, but the real eye openers are when he walks me through why that is, especially when he points out how much easier, faster, but more relaxed my eye gets to what it wants on a given page w/his designs vs. mine.
We've had 6 sessions so far and I'm convinced this is the best method of learning design (just as having a private tutor is superior for many other things). If you have someone you can hire for a similar arrangement, at least consider doing so, I highly recommend it.
[1][a] Designing Web Applications (Nathan Barry)
[1][b] The Non-Designer's Design Book (Robin Williams)
[1][c] Don't Make Me Thing (Steve Krug)