Should I restore my Iphone 4?

I got my iphone 4 from my friend and it got music and apps still on it. Should i restore it before i go to at&t to get a plan and a sim card?

If you want to, you won't need to though.

If you like the music than no, because the apps can just be deleted.

It's up to you if you want a new beginning with the iPhone 4. A restore will just erase all content and any apps/music.