If you spend an unusual amount of time evaluating, testing and just plain using websites, at the end of a long day, almost anything can seem like a interface conundrum. On the way home from work, I stop by the store for milk and veggies. As I swipe my card, I raise an eyebrow when I reach for the display: “Hmm…should those buttons be laid out “Cancel/OK” or “OK / Cancel.” Dunno. But I need the milk and veggies, so I just pay and go home.

Because I really do consider that particular interface question for at least a moment nearly every time I swipe my card, I smiled when I saw that Cancel/OK Vs. OK/ Cancel is the subject of Jakob Nielsen’s Alertbox column this week. Turns out that this is a question that nags at many developers, and that Jakob quite correctly puts in perspective:

In cases like this, it often doesn’t matter what you do. Either choice has good arguments in its favor, and no choice is likely to cause usability catastrophes.

Jakob points out that some interface choices matter a great deal more than others, and when in doubt it’s best to simply follow the norm for the platform in question. If you’re designing a desktop Windows app, follow those conventions. Designing for a Mac, follow Apple’s GUI standards:

Applying consistent design that follows user expectations saves people much more time (and many more mistakes) than doing something that might be a tiny bit more optimal for your application, but introduces an inconsistency.

Amen to that. And Jakob’s post is worth a close read for subtleties these quotes don’t capture. But I’d also venture another reason or two that cancel/ok (and other micro-usability puzzles) merit only so much attention.

Back at the supermarket, I swipe my credit card because I need the milk and I need the veggies. But most of us selling stuff online, are we lucky enough to offer something truly necessary? And for that matter, are we lucky enough to be the only site selling it?

You might sell fun stuff, cool stuff, relaxing stuff– but odds are that to one degree or another, the product you offer has been commoditized. Presenting that product in the most user-friendly, standards-compliant context is vital– but it’s often not enough to get the sale.

In our firm’s work making websites more effective, we find that embracing design and usability conventions is absolutely foundational, but is still only 1, critical dimension of success. What else matters? Giving people a reason to click that well-placed, intuitively labeled button.

How well does each page of your site convey your unique selling proposition? How effectively does your content seed the sale? Does each click forward maintain shopping scent? Do your pages persuade? Do they increase confidence and provide reassurance at the junctures that matter? Start with design and usability conventions, and then give your customer compelling reasons to click and buy. From you.