This guide is not meant to be as a whole and is not meant to be followed from beginning to end. There are several recommendations based on my own experience, some of them will give you big battery savings, some of them minor ones; I tried to recopile every config that helps to save battery, but every config is not suitable for everyone. (I´ll point it at the beginning of every section in bold blue).
You'll need a Rooted Galaxy Nexus, with a custom ROM and a custom Kernel.
The custom ROM will give you the ability to make a deep configuration of the device in terms of options. I'm actually using Liquidsmooth v1.25, but AOKP, CM9 and SlimICS have the same options (if not more) than my actual.
Some custom Kernels will give you the ability to change the CPU frequency and voltage, kernels are the main reason of some drainings or fantastic battery life, choose wise.
The normal Galaxy Nexus battery life is about 4 hours screen time. If you are not achieving this, the main reasons could be:
1. Some apps are draining your battery due to a continuous use (no deep sleep or continuous wake ups).
2. Screen too bright.
3. Bad kernels with draining problems.
4. Weak signal connections.
