Reading the guide that came with the computer is a good start. Mine recommended to remove the battery if the computer is expected to be used for several hours without needed to be moved, if the battery doesn't need charging.
The big killers, trying to charge a battery that's already full, heat, fully draining the battery and number of cycles.
If you won't need to move your computer and the battery is charged pull it to get it away from heat. Don't leave it in a hot car, or really anywhere with extreme temps or temp swings. Don't run on the battery if you don't need to. Try to slowly drain the battery, don't "full throttle" it until it's gone. Lower your screen brightness, turn down the volume, turn off and remove accessories, try not to run Prime95 (just an example!) and let the hard drive spin down at idle times. Don't let the battery drop below 20%. My manual suggested letting the battery drain as low as possible the first time to calibrate the charge indicator but after that to avoid it. Lithium Ion batteries have a limited number of charge/discharge cycles before the anode degrades.
Some would consider those measures extreme, some wouldn't. Pick the ones you feel are worth the "investment".