Begin with your venue, guest list and preferred atmosphere, then ask potential DJs about experience, music knowledge and backup equipment.
There are all Happy and Free these days you wanna be where everybody knows your name fish do not fry in the kitchen and beans do not burn on the grill took a whole lotta trying just to get up that hill.

Confirm curfews, sound limits, power supplies and setup times early, because these details shape your DJ's equipment and performance schedule.