Unless you schedule vacations regularly, be prepared for the possibility of burning out. Typical days are 10 hour shifts, typical rotations are either 5 on/2 off (think Monday-Friday), or 10 on/4 off (usually Monday to the next Wednesday). In either case, you're doing an average of 50 hours per week.
Though the various bonuses and per diem boost take home pay considerably, they pale in comparison to what you'd make with 20 hours of 1.5x overtime each pay period if you were non-exempt. Another reason to utilize your PTO! If you're of the "grindset" mentality and like cranking out long hours for months at a time with minimal time off, finding something that pays hourly rather than salary would probably be more fruitful.
If you're coming from a field like manufacturing, QA/QC, or aerospace, prepare for a culture shock. Depending on the project you're working on, SOP's may or may not be a thing, and if you are given an SOP or procedure, it's probably not up-to-date and will need adjustments. It's not uncommon to be reliant on tribal knowledge (if you're lucky), or exercising your Google-fu, scouring the internet for setup and user manuals for devices you've never seen before, from manufacturers you've never heard of. If you're a fan of following strict instructions for each task and having things go right on the first try, you'll probably wind up frustrated.
The work environments you're put in can be less than comfortable... You might be decked out in winter gear working in a -20°F freezer, or you could wind up sweating in a scissor lift 20 feet up in a 100°+F warehouse. For the most part though, expect vaguely climate-controlled indoor places, where you'll be wearing safety boots, safety glasses, and a hardhat.