things i can think of off the top of my head would be:
-install proper video card drivers so the power saver mode works.
-add the power applet to your bar and set it to power save mode.
-turn down the brightness on your screen, i would imagine this has to be done in the bios as i don't know if your specific laptop can do it through linux.
-turn off unneeded services that access different hardware you don't use. specific things would be bluetooth, wifi, etc.. having these things not constantly active and on means less or no power being used by them.
-try to cut down on the usb devices you use as this draws A LOT of power.
-if your going to be away from your laptop on and off for more then 10-20 minutes at a time set it so that your screen turns off while inactive. your screen draws a lot of power as well.
-try not to use the cd/dvd drive that much as this is another power drainer.
these are basic easy things i can think of off the top of my head. theres other more difficult things to do but ill let the pros guide you on them.
im sure theres more easy ones but...