This is not one of those "Turn off every useful feature of iOS" posts that grinds my gears. My goal is to deliver practical steps to truly solve your iOS battery woes.
One quick thing before we start — 99.9% of the time it is not actually iOS that is causing your battery to drain quickly. I guarantee you that if you erased your phone and there were no apps or email on it, it would last for ages. But, no one uses their device like that, nor should they. Hopefully with these steps you will be living in iOS battery bliss while still using all the apps and features you love.
If you've ever had iPhone battery life issues, or constantly get pestered by friends and family with poor iPhone battery life, this article by Scotty Loveless is a must-read. Unlike many rather sensational articles that suggest a myriad of 'solutions' that may or may not actually work, Loveless offers just a handful of rational and practical solutions and explains why he is suggesting them.