A phone is easily lost/stolen/broken. Make sure whatever important information (pictures, music, contacts, etc.) that's in your phone is backed up somewhere. For Android, Google already provides that service if you allow it. Apple has iCloud (I think).
There are tons of apps that can manage those backups for you.
Make it something automatic, because if you have to think about it, you'll do it for a week or two, then it will fall into "not right now, I'll do it tomorrow", then finally you'll just forget about it. Until you are painfully reminded that your last backup is over a year old.