Proper phone reset before selling?

[amro]

Now that my unlocked 4S has arrived, I need to make sure I properly clear the phone. Under normal circumstances, I would go to Settings->General->Reset->Erase All Content and Settings.

However, I'm reading about iMessage issues related to buyers of used iPhones with iOS5 being able to see messages sent to the owner's new phones. I'll be giving mine to some friends of mine, and I trust them, but I don't need them to be annoyed with my messages.

So, should I clear the phone with or without the SIM? Does it matter?
Should I disable iCloud before I clear the phone? Does it matter?
Do I really need to do anything other than the standard Erase All Content and Settings?

 

[Intell]

Plug the iPhone into iTunes and click Restore. When iTunes says "Leave the iPhone plugged in it is restarting", unplug the iPhone. It'll be at the Activation Screen, turn it off with the red slider and remove your SIM card. Do not sell it with the SIM card. Make sure the buyer knows this.

 

[TLewis]

Turn off iMessage before wiping it.