I'm not going to worry about battery - use the damn phone as intended and either charge it or swap batteries. Why should I have to cripple a device in order to try and get an extra few hours?
Draining a lithium ion battery too much will kill it. I drain mine to the red only once every couple months. Turn off gps when not in use. Turn screen down to 10. Blutooth off when not required. No apps other than the standard 5 running in the background. Being in a low signal area also contributes to heavy drain. This is what I have always done, always had good batt life.
1. Delete Social feed
2. Set backlight to 10
3. Auto dim + battery saving mode on
4. Interval refresh in apps at 2h or 1h for weather
5. Turn off bluetooth/wifi when not using them
6. Using a ram optimizer app can prevent you from memory leak
7. Make sure to close apps when not using them so they don't run in the background
Using a 3rd party theme can affect the battery life, same goes with some random apps.
By having this settings, I am rocking more than 24h of normal usage: texting, email, facebook and browsing... and sometimes gps. At 30h i'm still left with like 15-20%
I've gotten about a year and a half of battery life... Yes I am not kidding I have not charged my phone once since I bought it!
My secret:
When I bought it I charged it to 100% then set it all up with my email accounts and contacts etc... Then I took it off the charger and took the battery out of the phone and put my 9900 and the battery in a drawer in my desk... Haven't used my 9900 since but I'm sure the battery is still between 90% - 100%
Seriously people use your phones to your hearts content, there is a reason RIM sells car chargers and even extra batteries with charging cases for them!
What is the best way to get long battery use is it to drain the battery before charging or charge it when ever you can?
Just use it and enjoy. Beware of software that polls the server and you should be OK. Nothing you can do that will increase the life that much. The battery should last as long as you would want to use the device, anyway!