As has been said, BHO is a good option, but QWISO is a less dangerous extraction and is what I'd go for. Even if you made hash out of it a lot of THC would be left and you'd still get a good yield with solvents. Dry sifting like Ason suggests gives you less of a higher quality product than water extraction (if done properly), but if you make oil afterwards you save all the goodies anyway.