Restoring iPhone and backing it up?

-Well my iPhone 4S has been going in and out of 3G to the no service circle a lot lately so I've read it's Apple recommended to restore your iPhone.
-Now, my iPhone is backed up on my computer, but my question is, when I restore my iPhone back to factory default, am I still allowed to back it up after the restore so I don't lose all my contacts (300 contacts), pictures, etc.
-Idk I'm a total noob when it comes to backup and restore for the iPhone: p.

What you do is back up your iPhone, then restore to the previous backup. Itunes will give you this option, and they will ask if you want to go to a backup, or set up as a new phone after you restore it.