This is my first iPhone and theres a million topics saying a million different things. What is the best option for a new iPhone, should I let it run til its dead or charge it? Does it not matter?
Charge it nightly. Dont let it die very often (more frequently than a month). Dont charge it when its above about 80% (but this is not as important as the others I mentioned). Try to keep it above around 20%, unless youre doing a calibration of the battery meter. In short, make sure the ions are flowing in the battery (constant discharging and charging).
No disrespect nor insult intended but their are close to a dozen threads on this forum answering this question. On your next question you may want to use the search feature before starting a new thread on an old subject.
That being said to answer your question and maybe stop someone else from doing the same.
The iPhone 4 like its predecessors has a Lithium-Oxide battery. Your phone should have come with about an 80% or more charge. Use it like you wish, you do not need to run it down and recharge it. Apple recommends that you do this about once a month. Use it and have fun the battery life on the iPhone 4 is quite remarkable.
This info and much is available in a free iPhone 4 users manual in PDF form that you can download for free through the free iBooks app which I highly recommend. Nothing beats free.