Suggestions for protecting my database?

I have been using DEVONthink Personal for over three years, and have discovered it’s now over 700MB. If it ever became corrupt or lost, it would not be good. I backup my entire system HDD to a clone HDD, but was wondering what else I could do to protect my data.

Are there any “good housekeeping” practices in DT to keep my database healthy? Is there a maximum size for a DT database? Thanks.