Kevin Potts wrote a great article, 'The Details That Matter,' over at A List Apart. Here's the beginning:

A long time ago, in a galaxy far away, the graphic arts industry was populated by full-time illustrators, production assistants and compositors. With only composing sticks for laying out type, straight edges for defining grids, a human proofer to catch spelling mistakes and an arsenal of X-acto blades for making edits, these guys lived and breathed detail. Mistakes were costly. It was a trade position that required lengthy apprenticeship; job security depended on getting all of the little things right.

While many of the tactile skills needed for our new generation of PC-based web design and development are radically different, a critical eye for detail is as relevant as ever. In fact, because of the lower cost of entry and increasing commoditization of design, that eye for detail is not only necessary for staying afloat in the profession, but a requirement for success.

The functional details are different than the ones with which our forefathers wrestled. Most of us do not own goggles to prevent spray adhesive from getting in our eyes or loupes to gauge dot gain at a press check. We do, however, have to deal with the endearing idiosyncrasies of browsers; we all run into the same double margin bug and inconsistent JavaScript support. These are quantitative, documented issues. Good website builders like you and I avoid these altogether simply by writing better code. But the details that can kill a project faster than a fly against a windshield are more subversive: the ones that, in hindsight, should have been blindingly obvious.

Potts is spot-on -- it's the small details that can kill a project and ruin your reputation. You wouldn't think that clients have so little tolerance for error, but they do. Clients feel free to send you work rife with typos, poor grammar, and bad code, but you'll be expected to fix their mistakes; and may all the gods help you if you make new ones.

You also wouldn't think that an art director would be bad at details, but I am. I'm an abstract thinker. And when I say 'abstract,' I mean I naturally see patterns all the time, in everything. The big picture; the forest, not the trees. I'm such an abstract thinker that the human resources trainers who've put me through personality tests remark on it. Off the top of my head, I can give you an overview of… say, the Northern Renaissance, in which I cover the political, artistic, literary, philosophical, and religious movements. But if you asked me to tell you when the Hundred Years' War ended, no amount of torture could make my brain give up that date. I want to say sometime in the mid 1400s, but that's as far as I can go.

This has served me well in my career, because I can come up with an entire campaign easily. But it's also meant I have to fight extremely hard to proof my own work. Ye gods, that isn't easy for me. I'd rather jab myself with an X-Acto than proof my own work. And yet, if I didn't manage to do it, I'd be out of work, fast. So if you're also bad at proofing your work, and details elude you, here are some of the things I do to get around it:

First, if at all possible, I pressgang someone else into proofing it for me. And bribe them if necessary.
I initial every change a client's made to a proof, as I make it. This gives me a quick way to look back and see what I've done, especially when I get distracted and have to come back to the proof later.
I turn the proof upside down, and look at it again. This is surprisingly good for catching typos.
Pray to Titivillus, patron demon of printers. You laugh, but he's been around since monks were painstakingly writing on vellum, and blaming him for their mistakes.

Or, of course, there's always becoming an art director and making your minions do it. I like that one best. Be careful, though -- after enough typos, you'll lose your godlike status, as they see your clay feet.