Here’s a great video on how to remove a bottom bracket.
Also check out the most complete article on Square Taper Bottom Brackets available on the internet.
The focus is square taper or ISIS bottom brackets. The presenter shows what tools to use and how to use them.
He starts off with demonstrating different ways to get leverage in removing a tight bottom bracket.
Using a long-handled torque wrench is really the best way.
Avoiding cross-threading the bottom bracket as you are installing it into the bb shell is crucially important. The technique to avoid this problem is demonstrated.