I dont know if this stands true today, but I still do it. When i ever i get a new phone I make sure to let it die completly then charge it too 100% while off and i do it several times during the first week of having a new phone. Maybe crazy but people call it training the battery, that way it just holds its charge better. Right now I wake up at 7 take the phone with me, listen to music on the subway, use the 4g at work since im in lower manhatten quite a bit, watch some netflix during lunch, make calls and i got about 15% left around 7 pm listen to music on way home.. and I do play with it at home till it dies since its still my first week... but I am a firm believer on the whole 100 to 0 train the battery person.
Try downloading battery calibration from the Android market, it worked for me on my galaxy s2, and also do what maximusassamus says, that also helps a lot.