How Do I Control the Size of My Data.qdf File

Many years ago I got in trouble because my data file was too large. It was explained to me how to fix this problem I think on an annual basis. Time has passed so I have not only forgotten what I was told, I forgot to do it to. Any ideas what I was told? Or is it as easy as starting a new file every year? If it is, How would you get the accounts and year end balances to follow over?

JC