Jailbreaking Code of Common Sense
1) Never update your firmware before new jailbreak and unlock tools are released
2) Always save your hashes as soon as you get your phone (Use TinyUmbrella or Cydia once jailbroken)
3) You cannot brick an iPhone (other than a sudden hardware failure), they can be restored in DFU mode
4) Never delete any files/folders from your iPhone file system unless you have them backed up
5) If you buy a used iPhone, before you make payment, make sure it can be jailbroken (firmware version, bootrom, hashes saved by current owner).
6) SHSH hashes are device specific, they cannot be used for a different phone.
7) There will be no jailbreak for 4.0.2 firmware, ‘the team” is not going to waste an exploit on a temporary upgrade firmware version.
If you are on firmware 4.0.1 or older, install the .pdf patch so a malicious hacker cannot take control of your phone via a website.