Always put bait hives out and set them up as follows:
-Use a solid floor. I have never had success with an OMF, presumably because the bees don't think they can defend it.
-An old brood box and crown board that haven't been cleaned, so they still have wax and propolis on them. This seems to attract swarms better.
-One old comb inside if the bait hive is at home, a full box of old comb if it is away from home.
-A small entrance about the area of the end or side of a matchbox. Too big and you will reduce your chances of success.
-In the shade.
If bees become interested in a bait hive the first thing to do is to check your own colonies. Even though you may think they are alright, there is a possibility there may be supersedure cells or queen cells you have missed. If they are not your bees they could come from another beekeeper or a feral colony, so take the usual precautions to avoid the possibility of them being infected with foul brood.
If the bait hive is at home where I can see what is going on, I only use one old comb. When the swarm arrives I can shake the bees off, clip the queen and fill up the brood box with foundation. If the bees have put honey/nectar in the comb it can be burnt. If I use one comb away from home where I don't see what is happening I am likely to get a box full of wild comb, so I fill the box with comb and take a risk on the possibility of getting foul brood.