A. Get complete instructions for YOUR Tablet on how to ROOT or Flash. The most common reasons you will Brick your Tab is because you do not follow the instructions
B. Have a Copy of BOTH your current firmware and the correct firmware for your tablet for upgrade. If you do not have a copy of your current firmware, you will have no way to fix your Tablet, if you experience a problem with your new firmware
C. Back up your Tablet. This will usually require Rooting, so learn how to root your device.