Make sure you're using good weed. Otherwise decrease the amount of oil you use. I used an 1/8 of shitty mids and therefore only used like 5 teaspoons of oil. Still I had to take more than 2 to feel something.

I think if do 275 degrees for 2 1/2 hrs of an 1/8 of nice headies and 6 teaspoons of oil you should be good (make sure the thing you cook it in doesn't absorb alot of heat). I used a ceramic egg cooker, kind of looked like a ceramic shot glass. Taking two of these should give you very noticeable effects and three should give you a solid high for 3-4 hours.