1. Don’t install apps like task killer, which may consume extra power and make your phone unstable.
2. Don’t install any app for moving applications to SD card and waste your memory. It is all available in settings itself. Note: Moving app to SD still will leave some max of 50% on internal memory.
3. Battery booster and other apps claim that will improve the battery life. I did not see any much difference.
4. CPU tuner apps which switches the frequency automatically may give improvements on the battery life by reducing the Frequency. I doubt that stability of device in long run, because of frequent changes on the internal processing behavior. Note that these apps will run like services and will consume some power also.
5. if you want some extra internal memory, you can uninstall updates on Maps and other heavy application, and for which you feel the updates are not much useful.
6. Recently, I did factory reset and I could see some 110 MB internal memory and now i think i can install some apps. because, when i bought the phone and at the first time i checked, it was about to 50MB only. free. you may try that if you want.
7. if you are in the place where the phone signal is not good and consistent, I would recommend to off the GPRS or 3G if you want to save some back up time.
8. it would be good and best to charge always with the regular charger than the computer/laptop USB. especially when the battery charge is less than 15%.
9. it is not good one for gaming / heavy multiprocessing. you would feel the lag in performance. It is good for regular usage.
10. The built-in browser is good enough, i think.