This tutorial is a step by step guide to successfully Jailbreak and Unlock your iPhone 3G/3GS on Firmware 3.1.2 using BlackRa1n and BlackSn0w.
This tutorial applies to Windows and Mac users.
Before you Jailbreak:
Make sure to Sync your iPhone with iTunes prior to using this tutorial. Apple Store applications and personal information will be preserved.
Update your Firmware to 3.1.2 using iTunes (I will cover this point in Step 1 for those who don't know how to to this).
Backup you...
