1) Try to operate the phone between about 25% and 80/85% of charge. Fully discharging puts stress on the battery, as it's hard work for it to charge up from 0%; so does always charging to 100%.
2) Try to get a phone with a good daily battery life, to help you stick to 1) above;
3) Newer Android phones have a fast screen refresh rate in the settings (120hz or more), to make scrolling and gaming smoother. Switching this to a standard rate of 60HZ will save battery, and you may not notice the difference in screen performance:
4) When indoors, put the screen brightness down;
5) When you have finished with your phone for a while, make a habit of closing down all open apps. It's no great hassle to open them up again if you need them later. I've noticed that the camera app seems to suck alot of battery, so I definitely close that down as soon as I can.
6) Your phone will have all sorts of battery saving modes. These may affect the performance of your phone, but it's worth giving it a try. For example, throttling the maximum CPU speed will save battery, and you might not notice any degradation in performance if you only use your phone for web surfing and emails, especially if your phone has a fast processor to begin with.
7) Your phone may have a setting where it detects that it is in your pocket or bag, and will not switch on the screen if accidentally touched.
