On post housing.
The area I am in (KMC) has several area installations. You are allowed to get on the wait list for any of the installations, regardless of branch or rank. Some of the wait times are considerable. Most families will still need to find some kind of off post accommodations temporarily. When searching for a rental, be sure the lease is in a time frame you can handle. There are commonly month to month leases, year leases, "negotiable", & open leases. Wait times are always changing, so this month 4 bedroom houses may have the longest wait, next month it could 2 bedrooms.
There are stairwell apartments & town home style apartments currently available. Town home are obviously the preferred style, because there are no upstairs/downstairs neighbors, you have a small yard, you have your own garage (sometimes), each unit has it's own washer/dryer, etc. They are 3 bedroom & larger.
Stairwell may have 18-24 families in each building. One assigned parking space per unit. These are 2, 3 & 4 bedroom units. While not with all the amenities of town homes, people still enjoy these units & make them home.
Obviously on vs. off is a personal preference. Take the opportunity in your early days to drive around & get to know the areas you will be using on & around post. Knowing what each has to offer may help you make a decision.
Living on the economy.
Things are different in Germany than they were in the US - and probably even other OCONUS assignments you may have experienced. Pay attention the village/town the house is in. Is there access to public transportation? Are there any local shops/restaurants? Are pedestrian paths safe & obvious? How important are these things to you? The houses will all vary in style & size - just like in the US. Older homes may have narrow doorways & stairs. Basements may be finished & unfinished. Some rooms are set up oddly, or the flow of rooms isn't convenient. Many houses have upper rooms with slanted ceilings. Will your furniture fit? I suggest knowing some of the basic measurements of the larger pieces of furniture that you plan to move to Germany. Know the dimensions of sofas, tables, chairs, beds, dressers, desks, etc. Some people have had to push furniture through a window to get it in to the house. Consider what it would be like if you had to move on your own (without the help of professional movers). If you have a queen mattress, your box spring may have trouble going upstairs (you can buy a split box spring, though).
Once you have your incoming brief (spouses may attend & you should be allowed to have free childcare - ask someone about this ahead of time) you will be able to officially start looking for somewhere to live. You'll have your contract from housing (take them with you so you can get a signature if you are ready to take a house after viewing it), if you visit houses that are not listed with AHRN or the housing office - get a contract from that landlord & have housing look at it before you sign!
You will have to keep track of the houses you've viewed on a sheet of paper. Listing ID, number of bedrooms, and the reason you didn't rent it. You're not supposed to refuse it based on personal preference. Not b/c of distance to post, if it didn't have a yard or pet policy, etc. So make something up. My two favorite answers were: It was already rented/It was over OHA. B/c they were true. Every time. And I would never suggest any differently if questioned. ;) One quick tip - start keeping track of houses if you are browsing AHRN before you arrive. You can use those in your search - even if you never get a chance to see them. They'll likely be rented by the time you arrive - which is the reason you can put for not renting it.
If the house has already been rented before by an American - the housing office should have a file on it. You can request to see this file. It will tell you if any previous renter terminated the lease early due to an issue with the house. That may not seem like helpful information - but if you are looking at a year lease & 8 people in the last 10 years terminated their lease early - it might clue you in that several families were not happy in that house. This area is tricky, b/c some houses can have files here, or up in Baumholder - we're close enough for people to live here, but work at Baumholder - but not so close you'll want to drive over & peek in their file.
There is a person in the housing office that can help you set up appts & talk to landlords - you might have to bug a few people to get this help, but bug them! They can set up the appointment to see the house, meet you at the house to talk to the landlord if there is a language barrier, inspect the house, and help you later when you may need to speak to your landlord during the rental period. We ignored several houses b/c the landlords did not speak German. No one told us we could get help! We chose a house at the last minute so that we wouldn't get kicked out of our temporary lodging. We're not super happy with our first home in Germany (inconvenient location, wrong school district, no shops or convenient public transportation). Now that we know, we have a better idea of what to do/not do in the future.
Once your contract is signed, you can get an advance for the deposit...This either gets paid back by allotment or lump sum - you choose. You will get your utilities set up - varying opinions on this as to whether or not you should set up a direct transfer from the bank to utility company - some people have not been allowed to set it up without this, others have set it up this way, then changed it. Maybe it depends on the local companies. Schedule FMO to drop off your temporary items & your temporary-while-you're-in-Germany items. If you need phone & internet service the landlord may be able to tell you what is available in the village (not every village will have the same options or speeds). I won't go into specifics about which companies here because there are probably changes going on all the time. Find a local group on social media & get some advice from current locals who can make sure you find the right company. :)
A note on MOLD. Open the windows on each floor/in each room for a few minutes every day to clear out the moisture. You might want to do it more often in wet rooms like the kitchen, laundry, & bathroom. Chances are, except for winter your windows will likely be open pretty often anyway. In the winter - be sure to continue to do it! It really only takes about 10 minutes for the room to be freshened & aired out, then you can close the window again. Bundle up the kids...throw an extra blanket on, etc. But do it. If you fail to do it & a mold problem occurs you will be held responsible for it. Mold problems will not be an automatic "get out of lease" card.
Heat - many homes are heated with oil heat. It can be fairly expensive depending on how much you need & when you need it. If you can get several neighbors to order it together (your landlord might be able to help with this as well if he/she is familiar with the neighbors) it will be less expensive & ordering during a low-need time (like summer) will bring your costs down a little. Typically you move in to the house with a full tank. When you move out, you must leave it with a full tank. Check out the tank during your search for a rental. BIG TANK = BIG REFILL. If you have a very large tank, it may be indicative of the needs of the house. Also, keep your doors CLOSED. This will keep rooms warm without much effort. If you leave your doors open, the heat cannot be contained & you will waste a lot of heat.
There are also gas heated homes - that get filled monthly (usually) at a tank near the house (rather than in the basement like oil). The cost itself is usually similar to the oil, but b/c you spread it out monthly, it may seem more convenient/cheaper.
Wood pellet may also be an option, I do not have a lot of information on this, but if you end up with this type of heating system - be sure to clearly understand how it works & how you should upkeep the system.
Utilities - Some are metered, some may be included in rent. Just get the specifics & be prepared to pay for them. A lot of people want to blow their "extra" utility allowance each month, but it might be a good idea to put that off. The powers that be give you that much b/c they believe it will cost that much - based on their research about the costs in the area. Many homes that are metered pay an estimate based on the previous year's usage. What if a couple lived alone in the house before your family of 6? You might be paying $100 a month now for the electricity, but at the end of the year when the meter gets read - you may end up paying a lot more than that. Then again, if you are a couple who is renting in a house previously lived in by a family of 6 - you may be paying $300 a month & get a huge refund back (sometimes given as a check, sometimes applied to your account). I have heard some people (after paying what they thought was too much/little) requested a meter reading a few months after moving in so they don't have this problem. I don't know if it works or if the request is granted, but I'm sure you can ask! Water is done similarly - with the estimated cost, then actual cost configured later.
Incidentals - In addition to the regular costs of renting a home you may also be paying a yearly chimney sweep fee, trash collection, parking space, etc. One thing you might try to negotiate is to roll these in to the cost of your rent. If the rent is under your OHA cap then you have some room to work with. Monthly (these are estimates & just examples) chimney sweep - €20, monthly parking space - €40, monthly trash pickup - €30. The landlord can note on the contract that these things are included in the rental price. Then your utility allowance doesn't have to be used on those smaller costs. You do not get to pocket extra OHA. You might find a home over your OHA cap that you really love - but you should carefully consider this. The OHA is paid to you in dollars, but is paid in euro to your landlord. If the exchange rate does not favor the dollar, then what was once "just" $50 over is now $100 over.
I think I might have one more page to do that covers a lot of the extra information that people are always asking questions about like school districts, cell phones, insurance, banks, etc. I hope to get it up a little more quickly than this one! Keep your eyes peeled!