Modes

Hey David. I like your breakdowns of the church modes very much. I've a pretty good imrpoviser but i'm very limited to the pentatonics, blues scale, and every now and then i get lucky and an Aeolian note sounds good here and there. My question is really how do i know, and when, to use the certain modes. I understand to use minor pentaonic and when to use majors, but as far as the modes are concerned, i've been memorizing them, but i dont know how to apply them. any help would be appreciated