How to transfer contacts from my old iPhone to new iPhone?

I currently have an unlocked iPhone 3GS. I'm getting an unlocked iPhone 4S very soon and I'm just wondering if there's a way to transfer contacts from my 3GS to my 4S? I have iCloud turned "on" on my 3GS but I'm not sure how to use it from there if anything.

Your contacts should transfer over automatically when you connect your new iPhone up to iTunes.

Backup your old iPhone to your computer and restore your new iPhone from that backup. You can also go to a store owned by whatever cellular carrier you have. They can often transfer contacts for you in a matter of minutes.

Backup and restore using itunes

ITunes

Back up the 3GS
Restore from backup on the 4S.