In addition to what Drew wrote, you can take a look at your data base sizes in options and see what is what.
I'm guessing you are going to need to cut back or limit the apps you have installed. How many user-installed apps do you have?
Also, don't keep messages and BBM chats longer than you need. If you have keep messages set to forever, change it to 30 days. If you need to hang on to BBM chats, set BBM to save chat history to the SD card.
Same with calendar. if your cleandar database happens to be huge, get rid of what you don't need. Set the calendar to only keep old appointments as long as you really need.
As far as browser cache and history and that sort of stuff, I think if you are having to delete this to free up memory, you have other problems you need to fix first. Delete browser cache and cookies when the browser is having issues, but not to free up memory. My opinion.
I don't think contacts really take up a lot of memory for most people. But again, take a look at database sizes and see what is what. If you have thousands and thousands of contacts then maybe you have something to do there.
Finally, I'm not sure you could have saved media to main memory, but look. If you have saved video or pictures or music there, then move it to built in media memory or the micro SD card.