A rabbit one is a good choice and the most widely used. Not sure if you have a closed or open reed type call, but closed reed is the easiest to blow, however they do freeze up quicker in cold weather. When you blow one just try to put as much emotion as you can into it and draw out the end of your call as much as possible.

You don't need to be perfect with how you sound, rabbits do not practice their own dying calls and they only get to do it once. The key is to remain as motionless as possible and watch the wind, coyotes will almost always circle downwind.