LCD screens are serious power hogs. Most cameras have optical finders that are just like the ones found in film cameras. Every second you work without the LCD is several more minutes of battery time for shooting. Rule number two. Limit flash use.
Some people always shoot with a flash set for auto.
That means it is charged and ready to fire, even outdoors when it is not needed. Use the flash when you need it, but turn it off when you don't. Rule number three. Try not to spend excessive time reviewing shots while using battery power. Using the screen for an extended time exhausts the batteries quickly.