Well, Val (http://wifebehindthefire.com/tips-new-firefighter-wives/) asked for one tip, but I'm a wordy lady, and it's my blog, so...here goes!
Don't give into your fears
Don't let your overactive imagination run wild. FF being 15 minutes late from shift does not automatically mean he is dead in a ditch, nor does it automatically mean he's banging the local badge bunny. His relief was late, he ran a late call, he debriefed with the boys after shift, all of those are much more likely to be the reason behind his tardiness. Work out some sort of agreement that if he is going to do something after shift (like breakfast, the gun show, etc) that he text or call and let you know. Just because your FF hasn't returned your texts or calls in a few hours also doesn't mean he's in a ditch or banging the bunny. It most likely means he is at training, the chief is around, or, more likely than not, they've been running a ton of calls.
Don't identify solely as Fire Wife
I'm proud to be a fire wife, and proud to have a husband who loves his job and is passionate about helping people. However...I am not JUST a fire wife. I'm also a mom, an employee, sometimes a student, among other things. Even if someone is a housewife, get a pet for goodness sakes! Or better yet, get a hobby. Make friends outside of your FF. If you have nothing going on outside of the house, for whatever reasons, you have to make a life for yourself when he's gone. You won't survive this life, otherwise.
Don't text and call constantly
Your FF is at work, don't constantly text and call him. Would your boss be okay with it if your FF blew your phone up non-stop while you were working? Didn't think so. Not to mention, if he's not actively on a call, there's a good chance he is training, learning from the other guys at the house, teaching someone newer than him something, debriefing about a call with the others, or *shock* relaxing. I'm not saying don't ever contact him, but don't blow his phone up. I'm also not saying I haven't ever done this, because it happens. Sometimes the crap just hits the fan, and it's got a hefty chance of being on a shift day. When I'm able, I try to put it in an email, so he can read it later. Sometimes, that just doesn't happen. Work out a system for contact. For us, I text anytime I leave/arrive somewhere, so he knows I'm not dead in a ditch somewhere. I also typically text before bed. I may not always get a text back, but usually sometime during the night he will text me good night (I keep my notifications silent at night). Be reasonable and flexible with your system, however!
Be reasonable, be flexible, be forgiving
Firefighters are human, and I've yet to meet one that was omnipotent. They don't always know when a call will run long, when someone will get a flat on the way to work, etc. They also don't always know when they are going to have a decent night, or when they are going to have back-to-back calls all night. Side note, if it is a full moon, the night before, or the night after, it's pretty likely that they will be busy, in my experience. Try to not get angry/upset/hurt if he agrees to cover for a guy on the oncoming shift for an hour or two. First, you have no idea why that guy needs coverage (maybe his wife is in the ER, maybe he has a dead battery, maybe the sitter is sick, or maybe he just plain overslept), and second, some day, your guy will need the favor returned from someone, and he doesn't want the reputation of the county jerk burger who won't cover for anyone. With any luck, these guys will all work together for a LONG time - making enemies doesn't bode well. With that said, it's reasonable to expect a text or call to tell you he will be late because he's is covering for someone. Forgive him when he agrees to help out brothers (or sisters!) and it skews your plans.
For me, part of being flexible means avoiding making early morning plans when he is coming off shift, if at all possible. It also means having a contingency plan. Our son plays football, and we have to be on the field (sometimes over an hour away) at 0800 for morning games. If FF is running at behind at all, we have to go separately, which stinks (costs more in gas, then we have 2 vehicles there, etc). He tries to be first out when those games happen that way, but it doesn't always work. Sometimes he can get someone on the other shift to come in a few early, and relieve him. However, he can't do that if he doesn't know the schedule!
I absolutely recommend getting a shared calendar. We use Google Calendar, and it works through our various email accounts. He can see my calendar, the Minion's calendar, and I can see both of his job calendars (PT and FT), as well as "other" stuff, such as the company he volunteers with for charity stuff. I also have on my calendar (he'd have to log into my email to see these) my mom's calendar (I manage her healthcare), and my best friend/nanny's calendar. Calendar sharing is a WONDERFUL thing! Before I had a smart phone, I printed a blank calendar each month, wrote it everything, highlighted his stuff in blue, Minion's in green, mine in pink, family in purple, and other stuff in orange. Then, I made copies of it for the fridge, for him, and for me to have at work and in my purse. It helped, but was time consuming - now the online calendar does it all. I can look a month or year in advance and know if he is working, without counting days/weeks (we don't work a 1 on/2 off schedule here). It is absolutely worth it, and has really helped to not double book so often!
Don't assume female firefighters are the enemy
This has NEVER been an issue for me, but it comes up all the time. There was a female at FF's station when we met. That didn't mean she was hooking up with the guys, or that she was endangering them because women don't make as good of firefighters as men. That's all rubbish, in my book. She was just one of the guys, and I never looked at her any differently. Worrying yourself over a female FF seducing your FF is ridiculous and insecure. Don't do it, you won't survive the fire life being insecure. If your man is YOURS, nobody can steal him - it doesn't matter what profession he is in.
Maintain OPEN COMMUNICATION
Ask lots of questions, but don't push if he won't answer. Let him know how things are at home, but don't make every call or text a massive complaint session. Show him you care about his job, but let him know you expect him to care about yours, too. He's going to go on bad calls, and not all fire wives can handle hearing the details. If you can, let him know that you are willing to listen. If you can't, make sure he has some sort of outlet for talking about them. We email a lot, because it's easier between our conflicting schedules, and because he's not much on talking most of the time. Whatever you do, keep the lines open, because open communication is key to a successful relationship, especially in a world where our significant others are gone so much of the time.