So I am ready to upgrade from my 3G to the Iphone 4. I am going to sell the 3G, so I would like to jailbreak & unlock it. The new Iphone is still in the box. How should I go about this process? Should I jailbreak & unlock the 3G first, then activate the I4? Also I would like to clear all the data from the 3G so I leave no info on there. When during the process should I do that?