If you don't know much about calling elk, I'd pass on a call. Quiet is better than wrong.If you really have to have one though,look at any of the Skeery cow calls
A wrong call or call at the wrong time can send the elk into the next drainage about as fast as if they smell you
I agree with the above posts, don't call until you have an idea of what - and when - to use one. You are as likely to blow out the elk, as attract them.
In 2012, I got into a little valley in Unit 4 in Idaho in the mid-day to early afternoon. The valley was alive with bugles, there were elk there, and at least two bulls were taken that day by other hunters. I sat and listened, trying to sort out what was were, and who was what. I made a couple calls myself and had too many replies to be all elk...it was almost humorous. I finally backed out, and decided to come back in the next morning, from the other side.
At this point, I'd met one party coming out - they'd seen too many hunters. I had an out-of-state motorcycle come down the trail packing out a bull in the no-motorized area, met another hunter packing out a bull from opening day, and generally figured it was a going to be a long day without much action.
The following morning - I walked in to a point in the trail where I could break off and move to a hillside that seemed passed by with the crowd of hunters. I sat and looked, glassed the valley, and planned a route for the day. About 5 minutes later, I had a 6x6 on the ground that was trying to sneak out of the area. He walked up on me out the brush about 60 yards away, and was trying to figure his route out of the area.
Point being - all the commotion the previous day had run this bull underground - he was sneaking out.
If you have to take one - take a Primos Hoochie Mama Cow Elk Call - if you spook an elk or a group, a quick squeeze on the Momma may stop them for a second look. It's pretty easy call to use, and leaves less to chance.
The bad news - about every hunter has one...
If you are going as a hunter, you shouldn't be calling, your partner should be - from some point behind you.