So you're in the diligent/fortunate subset of the population who already has a FICO score over 720. Congratulations! Through a combination of wise financial stewardship and good luck, you've managed to avoid the slings and arrows of FICO-lowering events, and are sailing through clear waters. The challenge to you, then, isn't to gain good credit, but rather to maintain it.

The first rule to maintaining your good credit is to pay everything on time. Do this, and you'll never have to worry about your credit score taking a significant drop. This is far and away the number one consideration for keeping the gleam on your FICO score. Sure, a change in your credit mix, the aging off of old closed accounts, or the establishment of a new account may jostle your score a bit. But if you're at 772, you're not going to suddenly drop back to, say, 703. Unless you're just 30 days late on some teensy bill that gets reported, in which case you could tumble all the way back to the upper 600s!

Second, avoid applying for a large amount of new credit. You don't need additional lines of credit to improve your score, and opening several new lines will cost you in terms of average age of accounts. Note that going from 12 to 6 years in this stat won't dump you into subprime hell, but it could turn a nice 778 into a merely respectable 731 or so.

Third, guard your oldest account, especially if it's your oldest by a significant margin. If your oldest account is inactive, consider activating it again if that's an option. Otherwise, it will drop off your credit report ten years after the date of last activity, and you'll lose that history. As already stated, not the end of the world, but it would be something of a bummer.

Fourth, mind your utilization. If you go on a shopping spree, expect to pay for it with a lower FICO score, especially given that you're already 50 to 100 points above the average, and FICO loves to look for ways to regress you back to the mean. If this happens, you can always pay the balances down and regain your points within weeks to a couple months. However, you don't want some snooty credit-card company noticing a plunge in your FICO and jacking up your rates or whacking you with a credit-line decrease.

Above all, congratulate yourself! Millions of people would love to be in your shoes. Just exercise a little caution and don't run with scissors or swim immediately after large meals.