Treat your battery well. All info are available on Apple website but here a few tips from my experience
Batteries have a lifespan, which is measured as the number of times you can recharge them.
To exploit a recharge cycle at its best one should fully recharge the battery every time and use it completely.
Is this enough? Nope. Somewhere I have read (and I cannot find where!!) that after a full recharge one should either let the battery rest for 2 hours before working on the laptop, or work the first two hours while keeping the laptop plugged. Apparently this keep the lithium ions flowing, but I cannot really say whether this is the case. On the other hand I have done it since I bought my MBpro and after 2 and a half years of daily use my battery is still at 90% of its capacity.
Is it the battery or the counter? Everywhere it is suggested that the battery should be kept calibrated and this means to perform some resetting operations every months. Best explanation I found is here or here, but if you like apple instructions better, here they go:
Let your laptop fully use the battery (and go to sleep) at least once a month. At a Genius Bar I was told not to let it do too often, it should be just once a month. Here some more tips from Apple.
Reset your System Management Controller (SMC). Here a list of what to do
Power off
Hold ctrl, option and shift
While holding these three keys down, press and hold the power button as well
Hold these four keys for at least 10 seconds
Power back on
Reset your PRAM. Here a list of what to do
Power off
Locate command, option, p, and r
Power on
Press and hold the four keys (command, option, p, and r) before the grey screen appears
Hold the four keys (command, option, p, and r) until the mac restart and you hear the startup sound for a second time.