These are a few basic tips I stick to:
1) don't let it get too cold, if your battery gets too cold it will lose charge, this is why your phone will magically die even though you just charged it when you're outside in the winter. If your battery ever ends up getting rather cold, try to warm it (just taking a phone battery in your hand and rubbing it works fine- I guess this doesn't apply to iPods/iPhones though because of no removable battery)
2) this is pretty much a no-brainer, but don't block your fans
3) Some people say don't overcharge it, this mainly is an issue with older 90s era electronics, but doesn't factor in now as as I'm sure you more than know, electronics are so much smarter today
4) Clean it/make sure it doesn't get dirty, this is actually really good when applied to cars, cleaning corrosion on the terminals of a car battery can add up to a year or more to the battery's life. Periodically check all batteries, especially when hidden inside like with iPods, for cleaning.
5) Only use good chargers, don't try messing with strange 3rd party who knows what chargers, I do my best to avoid them, some people like saving money, others like not taking risks with batteries (and strong electric currents in general!).
6) Common sense: Should I see what noise this battery makes when dropped from different heights?
Number six is key.