As the iPhone 4 approaches its first birthday (and previous models approach their second, third, etc.), it's time to start looking at ways to improve battery life. After all, it's around the one-year mark that most batteries start to lose some capacity, meaning your phone simply won't run as long as it used to between charges.

New York Times tech columnist David Pogue recently got four iPhone battery tips from an Apple store Genius--some of them obvious, some not-so-obvious. Here's an overview of the advice, along with my thoughts and two additional tips from yours truly.

Turn off push e-mail. No doubt about it, forcing your iPhone to check for new mail every 15 minutes--especially if you have multiple accounts--will kill your battery in a hurry. It can kill your productivity, too. Tell friends and co-workers that if they need to reach you urgently, send a text.

Turn off location services. A lot of apps tap the phone's GPS when they don't really need to. Head to Settings, Location Services, and disable the feature for the apps that can live without a location check. (I'm looking at you, Angry Birds!)

Turn off notifications. While you're in the Settings app, tap Notifications and turn off all unnecessary sounds, alerts, and Home Screen badges. As Pogue points out, the apps that use these features have to monitor your iPhone--and that uses up juice.

Manually terminate background apps. Apple says background apps aren't technically "running" unless they're front and center, meaning they shouldn't be drawing any power. Pogue's Genius says otherwise, and that you should manually shut down all background apps. I disagree, as I think the hassle of constantly monitoring and terminating apps isn't worth the battery boost you might get. (Pogue cites a friend's dramatic improvement in battery life after following all four of these tips, but I think turning off push e-mail made all the difference.)

Lower the screen brightness. Nothing sucks up juice like the screen. If your brightness setting is cranked to maximum, knock it down to 50 percent. You won't like this at first, but I guarantee after an hour you won't even notice the difference. You will, however, get longer battery life.

Keep it out of your pocket. The hotter your iPhone gets, the faster the battery will die. And you know what's in your pocket Body heat. If you can, let the phone ride shotgun in your purse or briefcase, or keep it clipped to your belt.

By the way, if your iPhone is out of warranty, consider replacing the battery altogether. That's one sure-fire way to keep it running longer, and it's easier and more affordable than you might think. (Watch for an upcoming post on replacing an iPhone 4 battery on the cheap. In the meantime, check out Replace your iPhone 3G battery for $6.)

Got any battery-life tips of your own to share Hit the comments and impart your wisdom.