Well, I learned that you generally want to have a full backup on Friday's based on system use and on recovery issues. By backing up fully on Fridays, you have not lost a full weeks worth of work. If there is a problem during the week, then you only need to restore incrimentals up to that point.
I also, learned (and this is all from experience) that it pays to keep at least three generations of backups. Something once called the "grandfather, father, son" principle. :) Might be showing my age with this one. At any rate the idea is, that you keep a full backup on a media, then the next full backup is on a different media, and the third is on still a different. Now you can rotate the three media starting at the oldest.
I saw a lot of good posts about verifying your backups. This is cruicial as I uncovered early on in my career. You never know. If I remember one of the posts specified that you were backing up documents. I had a user save their files with control characters in the name - I still haven't figured out how they accomplished it - and that caused the backups to be bad.
Just something to think about in my opinion. Good Luck