My 2 favorite mouth calls are the Crit-R-Call 'Pee Wee', and the Burnham Brothers 'Mini-Blaster'. Both should be available at allpredatorcalls.com.
Scout ahead of time for thick cover likely to hold coyotes/predators, away from human activity. Get into position SILENTLY on the downwind side, sit rock still. Try to do your 1st tweet just as it's light enough to shoot. Keep hunting into daylight. Make new sets out of hearing of the 1st & keep trying. Just when you think nothing will happen, you are surprised. Watch a DVD or 2 from Randy Anderson or similar.
I have a Foxpro but often as not I like mouth calls.