It's basically an automatic response. Your brain senses idle mental cycles and your hand reaches for the phone in your pocket. Next time you're standing in line at Chipotle and tempted to palm your digital pacifier, try this instead: observe your surroundings. No, really see the things around you. Study them and engage your grey matter.
I've been trying to do this more often lately. It doesn't come naturally, but at least once a day, I try to practice my observation skills. I think it's an important and healthy skill to cultivate. I also believe it is crucial for improving the level of your professional craftsmanship.
When that terrifying drop in mental stimulation happens, simply look around and pick an object to think about. If you're in line at Chipotle, maybe you zero in on that metal fence that separates the people in line from the patrons at the burrito assembly line. Look closely and ask yourself every question you can think of. How many pieces of metal were welded together? Why is the paint more worn right here? How is it mounted to the floor? How many bolts are keeping it together. The hipster up ahead just leaned on it - did it give or flex at all? Why or why not? You get the picture.
David Foster Wallace was one the masters of hyper-descriptive writing. Neal Stephenson has also written some passages with near-comical levels of detail (the Cap 'N Crunch piece from Cryptonomicon comes to mind).
The powers of observance of these guys, though, are dwarfed by a guy named Nicholson Baker. I recently read his book, The Mezzanine in which the main character simply recounts what he observed during a single lunch hour. That's the entire book. It's a quick read and much more amusing than it sounds. If nothing else, it shows how many things we look at every day and how little we actually see.
In our fast-paced industry, I think we're all guilty of keeping one eye on the firehose of today's new and shiny and the other on what might be coming tomorrow. We rarely slow down and take the time to learn from what's here right now.
I think Dribbble is a good example of this. It seems that most users see a great shot and immediately leave a "So sexy, I love it!" comment and move on. This isn't all that useful to the designer (unless they have an insatiable ego) and the commenter isn't taking anything away.
When you come across something that you like, stop and try to figure out why you feel that way. If you're a designer, take a closer look at that Dribbble shot. Why did it grab your eye? Did you like the blue used on the button? Maybe that subtle highlight at the top gives just the right amount of contrast against the outer stroke? Maybe the stroke isn't a solid color, but a subtle gradient from top to bottom? Maybe the barely-perceptible drop shadow (or lack thereof) isn't something you wouldn't normally think to do, but here it's really working. Open up the loupe tool in xScope and study every little nuance. The designer spent time on all of those little details and they'll appreciate your feedback on something specific.
I've noticed that the best designers never produce small icons with blurry line work. Most of us will never be great icon designers (myself included), but there are some techniques we can learn from them.
Pixel hinting is a small thing I learned about not too long ago and it has drastically improved the quality of my icon work. I'm no icon designer myself, but I often use glyphs from amazing sets like Pictos, Picons, and Geomicons. Making these vector icons look crisp at small sizes takes a little extra elbow grease.
I've known about Photoshop's Snap to Pixels setting for a long time, but this alone isn't enough. If you turn on the pixel grid, zoom in on your glyph, and see that some anchor points aren't sitting squarely on a pixel, you're going to have anti-aliased (blurry) edges. Take a few minutes to adjust these point and you'll end up with a much nicer looking icon. Phil Coffman has a great screencast on pixel hinting at Method & Craft. This is just one of a million small ways to level up your design chops.
Seeing: it's not just for designers
This type of OCD-level attention to detail shouldn't be practiced by designers alone. If you're a developer, pay attention to the technical attributes of software that you use. If you've found a great Rails plugin, don't just drop it into your project without a second thought. Open it up and see how the author solved the problem. Is it the same way you would have? No? Why not? Can you think of a better way? Yeah? Run it by the author. Win-win.
If you're a manager, try to pick the brains of collegues who've had big successes. Don't just ask the superficial questions - go deep and uncover the tiny details.
Once you have proficiency in your craft, mastery is all about the details. This is an endless process of learning and constant improvement (see: kaizen). Our skills are simply an aggregate of everything we've absorbed so far and we'll absorb much more if we slow down, study, and contemplate.