Turn down the screen brightness
Look into notifications. it defaults to everything being on and you can turn off most if not all of them.
Check your e-mail. If it's on push that means it's reaching out for new mails every so often, turning it to fetch means that it only goes to get mail when you tell it to.
Look at some of your apps. Some of them may be doing things in the background that you don't realize and you can tweak those to not run when you don't need them to run.