How should I wipe my phone before selling? (i4 on 4.0)

[asbenw]

Well, I'm going to sell my iPhone 4 in a week or so. I've been setting up my iPhone 3g for use until an iPhone 5 or good android phone comes out for AT&T.

I've been reading around, people say to use the "erase all content and settings" option, but I'm extremely worried about that because when I did that to my 3G, it got stuck in a boot loop and I had to restore on iTunes.
I also cannot restore with iTunes because I want to preserve the 4.0/01.59.00 firmware and baseband since it makes the selling price considerably higher. I do not have the 4.0 SHSH blobs saved, the lowest is 4.0.2.

So, my question is, what should I do to erase my phone before selling it? Should I sync it with another computer so that it erases all apps, musics, etc? What about e-mail, itunes account, contacts? I really need help with this.

Thanks in advance!

[Stray]

Go to 4.0.2 using the shsh's the baseband will stay the same

[asbenw]

Is there any way to delete everything staying on 4.0?

[Stray]

You can delete all the contacts then delete all music remove account and pictures and any other personal info and u should be fine

[HappyTroller]

Baseband preservation mode in sn0wbreeze and create a preservated cfw. (if u have 4.2.1 blobs only)