Have a medium to small sized pair of channel locks, preferably knipex, pencil/pen, small pad of paper, and under no circumstances do what that hog character said and show up with a stick rule. You will Likely be ridiculed on the west coast. 16' standard tape or 25' if that's what you have. No bob the builder crap and no monster 35' Milwaukee thing. Get some comfortable and light boots especially if you're in construction. A lot of guys don't wear what ironworkers and carpenters wear for boots because we stand/walk on concrete or car tops all day. Keen steel toes are highly recommended around these parts. Break in whatever you get before you're hired! I've seen a couple probies have to quit due to horrible blisters on their feet.
Also I will mention one thing I learned from an Otis foreman (and an old copy of their union master agreement) get certified for nr232 in all positions, if you are certified to weld and perform welding of any sort you get mechanics pay aaka 63 an hour not including the bargained raise they got last July.
I've been inspecting the structural half of the elevator guide rails that the iron workers put in for years and have talked to many elevator foremen.
99.9% of us went in not knowing what questions to expect, so in all fairness you should too. Just prepare yourself for general interview questions and some regarding your experience.
You have about 15-20 minutes to sell yourself, bring copies of all supporting documents for any licenses or certificates you may have. Be 100% you, don't try to answer in other ways that are not you, because interviewers can see through that. Wear slacks/khakis and a nice button up, don't need a suit.