Alex's list of energy saving tips includes:
- Dimming your display; a laptop's display accounts for the largest proportion of energy used
- Switch to the on-board/integrated graphics card; many modern MacBooks have two graphics cards, use the least power hungry
- Adjust sleep time; use Energy Saver to put your idle Mac to sleep sooner rather than later
If you want to do more and save more than Energy Saver can offer, try Power Manager.