Bad battery life is usually attributed to one of the following:
1. Not fully discharging the battery
2. Post-upgrade cruft (installing OSX Mountain Lion over Snow Leopard or Lion)
3. Lack of sufficient hardware
4. Psycological reasons (power of suggestion)
5. Too many network requests (iCloud, Facebook/Twitter integration, automatic stuff), can be a number of failed network requests due to an update
Course of action:
1. Fully discharge battery and fully charge it again. Do this as often as possible, but at least monthly
2. Just try to stop caring about the battery indicator, hide it and surf the internet and see if you can break the power of suggestion. Also, don't read too far into forums, they tend to be negative.
2. If there is no change, try upgrading your RAM (to 16GB 😀, its probably $50-$70 now, Crucial is a good company), as Virtual Memory can sap your battery (keeps the drive in constant use). Watch YouTube videos of RAM installation it before doing it, and remember to touch the metal of the optical drive to discharge static electricity before handling the RAM. Also, handle the RAM with care, touching it only by the edges. You CAN rest it on the black modules.
3. Clean install/SSD upgrade. SSDs use less energy and are MUCH faster. If you are doing a clean install and you have $100-$200 lying around, buy an SSD. Clean installs are often a good idea because they are, well, clean.
IMPORTANT: There have been many problems with the SandForce controller, so don't buy a SandForce powered drive. A good way to tell that a drive is SandForce powered is if it comes in 60GB, 120GB, 240GB, 480GB sizes. I would go for a Crucial m4 or an OCZ Vertex 4. I have used both drives and I would recommend them to anyone. The OCZ drives are a tad faster, but they are still a bit of an unknown, considering the flop that was the Vertex 2 and 3... The "sweet spot" for price vs performance is usually 256GB. Don't buy 512GB drives because they can be a RAID0 array of 256GB drives.
A guide to optimize SSDs for mac is HERE. You should enable TRIM and disable hibernate.
The best screwdriver is HERE. I know it's for oboes, but the different bits can fit any screw on the MacBook Pro (yes, even hex screws if you use the right bit, usually the biggest). Use the smallest bit for the screws on the back of the shell.