Battery Problems please help!!!!

There is no easy answer for your question. Could be something like trunk or glovebox light always on.
Part stores can check a lot of the charging system and components. Rule out the common stuff like battery and voltage regulator first then anything you've added like amplifiers and sterios, then start looking for those flaws that come with age like amp gauge, bulkhead connections, etc...
On a comical note "I've bought 2 batteries and 2 starters. I've owned the car 19 years. " LOL Good luck