You've got a great subject, you've lined up the shot perfectly, checked your settings and adjusted for the environment. Then you press the shutter button and . . . nothing happens. There are few things in life worse than the feeling you get when you're about to take a photo, only for your camera's battery to give up on you. Although modern digital camera batteries usually last quite a long time, that can be a problem in itself, as you're more likely to forget to charge it.
Carrying a spare battery and keeping on top of charges is one way to avoid running out of power on the move, there are some simple things you can do to maximise battery life so you can make the most of each charge.
Use the viewfinder
Most modern digital cameras, particularly DSLRs, are equipped with both a viewfinder and an LCD screen. The screen is used for all sorts of things, like editing settings and looking at pictures you've taken, but one of its functions is as a preview for an image, in lieu of looking through the viewfinder. While some people find this convenient and easier to use, it's better to get used to using the viewfinder, as the screen being on all the time is a major battery drain. It will also help you compose better pictures.
Check your format
Serious photographers shoot in RAW, but do you need to? RAW is an image format that maximises quality and makes editing more powerful, but this may not be useful to you. If it isn't, switch to JPEG shooting, which will use less battery.
If you can move physically closer to your subject, that's a much better option than using the zoom. Zooming the camera's lens involves little motors kicking in, spending your battery power. Moving the whole camera closer will give you better quality images, as a bonus.
Use a separate flash
Attaching a separate flash unit to your camera will use its own power source rather than the camera's. It's another battery to worry about, but it spreads the strain to help your internal battery last longer.
Check through your settings
Look for any settings turned on that you don't actually need. There's a good chance switching them off will use less power, saving your battery. Things like long exposures, burst shooting and GPS will drain a battery fast, and some settings may be sitting switched on in the background without you immediately realising.