I've been in the process of converting for several years. I certainly wouldn't claim to have "arrived" yet, but I think the process has been very good for me.
It seems trite to say, but I believe that it's all about doing it. The most useful thing I've found (and I do this not just with design, but with programming) is to find something I like, and then re-create it. I'll see a shot on dribbble (http://dribbble.com) and decide to create something similar from scratch, by playing around in Photoshop until I get it right (or close). If I get stumped, my last line of defense is to look up a tutorial on the look I'm trying to achieve.
I would never publish anything I've created through this method, but the act of purposeful creation gives me tools and techniques to use down the road.
It seems trite to say, but I believe that it's all about doing it. The most useful thing I've found (and I do this not just with design, but with programming) is to find something I like, and then re-create it. I'll see a shot on dribbble (http://dribbble.com) and decide to create something similar from scratch, by playing around in Photoshop until I get it right (or close). If I get stumped, my last line of defense is to look up a tutorial on the look I'm trying to achieve.
I would never publish anything I've created through this method, but the act of purposeful creation gives me tools and techniques to use down the road.