Which outfitter? Usually I find that they pick which ranch you'll go on which day.
Pray for snow. Lots of it. Then pray for more.
I was there a year ago when it was 30 at night, 50 during the day, and no snow worth mentioning. As a result the elk weren't pushed off the mountains so we never saw one. At this time of year your success will depend on the herds being pushed down as well as lots of luck if they're not.
Per the webcams, I don't see any appreciable snow there now...