I've always hated the work HST take when you want accurate units! You end up having to square each individual one... that is until I found the paper foundation method.

Foundation Paper HST Method: http://www.katiesquiltingcorner.com/...-easy-and.html

Depending on the size of the triangle you can make LOTS of units with one piece of paper - all ACCURATE!! I'm doing all my HST this way now. I had to do over 300 for the Bonnie Hunter mystery quilt and this made them so fast to do.