A few tips;
Discharge the battery to 0% and then up to 100% at least once a month will help a lot.
If you are not using the internet turn off; 3G, cellular data, wifi. And if you want to connect only use one at a time. (Having wifi on without using it still uses battery)
Turn off bluetooth until you need it.
Turn off push notifications if you don't need them.
Do not use jailbreaks as they often make the battery performance worse.
Turn down the brightness.