You should keep WiFi off unless using it, same with bluetooth. I don't know if apple has a screen brightness setting or not, but I keep mine darker, I have an android phone.

Also another thing is to keep your 4g off and instead use 3g. The reason being is not every place has 4g so if you're in an area without it and your phones constantly searching for 4g signal it'll eat the battery up.

I have about 100 more things I could tell you but I'm not to keen or upkept on apple phones for the simple reason I never liked their products. Wish I could help you out.