Backing up. and getting some organization with backups

Hello there.

When doing a Full computer backup, with paragon backup and recovery software, and then you do a certain aount of differential backups, When really should you do your next full backup.

(ie. you could go on creating differential backups until you run out of space, until you decide to delete some, but what about the full backup, when really should you delete this and create a new one.

Or can you just keep the first original full backup and use this as a base all the time.  

I am just trying to get my backups in order, and was making sure if i am doing it in the correct way, i know its all down to personel preference, but sometimes i get into a mess with backups, and maybe creating full backups when there's no need to.

My situation.
I do not generate a lot of files, a few maybe every other day, and i have just done another full backup and deleted all the old ones.
So all i have now is 1 full computer backup on the machine, so to get some order and organization what generally should i start doing to get my backups in order....