I generally start with a prey (rabbit) and then move to howls. Lots of them paired or pairing up now so sometimes start with howls.
Randy Anderson said he never scared one away starting with a howl but I think I have. Sometimes have thrown the kitchen sink at them. Remember one I tried everything, rabbit, birds, rodent, howls, fawn, and he just stayed out there. Finally tried kitten cries as a last hail marry and here he comes. Go figure. Just kind of by feel of the territory I'm in, experience, and educated guess all thrown in together. I've been night hunting 3 years and before that very difficult day hunting here. I'm still learning. I think the main thing is to try to put down your target. If you miss, you just educated one and that's one thing I try not to do.