I.M. injection in hip....

Hi, I'm a new LPN, and was wondering what is the best way to find the appropriate site for an IM injection in the hip/butt? I was taught to used the 4 quadrants method & divide the butt in to 4 quadrants, but I see so many nurses find the site differently. I give it right under the hip bone, using the 4 quadrant method. But I have seen many nurses give the inection low, several inches under the hip bone... this seems kinda close to the sciatic nerve to me. What's the best way to find the site? Thanks.....