Great thing about non-iphones is that you can just buy more batteries. But before you do that there a few things you can do that make a huge difference is battery life.
Turn off 4G when you dont need it
Turn off Wi-Fi when you dont need it
Turn off GPS when you dont need it
Turn off Bluetooth when you dont need it.
See the pattern? Those 4 features will eat most of your battery life if left on
The other culprits are games, music, streaming video, flash heavy websites, etc.
And lastly, applications that have auto updates or are constantly pulling data from the network. Apps that regularly update feeds like Facebook, Twitter, ESPN, Weather...
In settings just go to manage applications and you should be able to limit the frequency that those apps request updates through the network. For example, I know you can do that with Facebook through your phone. You can literally set up the app so that you dont receive certain types of status updates and you can control how often it connects to facebook to grab info.
You might not realize it but the facebook, weather, and news apps grab data feeds every hour by default so if you are in an area with a 2 or 3 bar signal your phone is going to work 10X harder just to try to boost the signal so it can connect to the host server through the network.
All the things I listed will get that 4 hour battery life to maybe 8 or 10 depending on talk time, apps, internet use etc.
If those things dont help search your battery on ebay. You can probably get 2 batteries for $5 through one of the Chinese ebay sellers. I have 4 and they work fine. Only last about 6 months but in that time you have a new phone anyways. Plus they're about $30 cheaper than branded HTC batteries.
Hope this helped.