Zombie Dart! '72 Dodge Dart

When you do bending by hand, don't just grab it in one spot and bend a 90. Start at the beginning of the bend and move along the curve gradually, then restart at the begining of the bend again and bend it a little tighter along the bend again. It spreads the stress of the metal out, instead of placing it all in one spot, causing it to kink.
I hope it sounds clear enough....