For many musicians, the luxury of a spacious basement or garage that's actually attached to their domicile is little more than a distant dream from a parallel universe. For some of us, the confines of city living and the thin walls of the average apartment force our sonic activities into minimal, overcrowded and often grungy dens of noise known as practice spaces. Practice spaces range considerably in their amenities and quality, from pro-level studio spaces to barren hovels that amount to little more than storage cubbies with power outlets. But wherever your particular space falls on the spectrum, there are some undeniable guidelines all players should follow when sharingtheir music space with others.
Don't Use Other People's Gear Without Expressed Permission
For someone who cultivates and cares for their gear to an obsessive degree, there's nothing worse than the realization that someone else has been using it. Even just a subtle change in settings on an amp EQ can send your average gearhead into frenzy of suspicion as to who's been using their stuff.
If there's even a shred of a doubt as to whether you can or cannot use someone else's gear, don't do it. Just remember, most musicians have been in the same bind that you find yourself in and are sensitive to the fact that you need an emergency kick pedal or power supply. All it takes is a simple request. You'll likely find that, in most cases, your space-mate will be happy to help you out.
In cases where there is shared gear like a P.A. or recording rig, it's common courtesy to revert settings to where you found them. If you need to move someone else's gear to make space for your rehersal, try to stack it neatly and orderly as a sign of respect.
Pay Your Rent On Time
This may seem like a total no brainer, but sharing a practice space is one of those situations where friendships and finance can come dangerously close to one another. These can be choppy waters to navigate, especially if you're in a situation where one space member is responsible for collecting individual sums from everyone else and cutting the final check to the management. In some more modern facilities, online individual payment portals exist which can alleviate this tension, but in any scenario, do not leave your bandmates hanging when the end of the month comes around.
There is a similar sub-rule to this: Never for a moment assume that you don't have to pay or are responsible for less than your agreed-upon share in a given month. Even if you only used the space once, you've made a commitment and owe it to your musical kinfolk to hold that up.
Leave It Cleaner Than You Found It
Treat your shared space like a campground in one of America's many majestic state or national parks. If you arrive at the space and there are uncoiled cables and dead strings on the ground, take a few minutes to tidy the place up when you're done playing. For all the hundreds and thousands of dollars musicians invest in stocking their space with gear, there's often one very crucial piece they miss: a trash can. It's amazing what a designated place to throw your garbage can do to keep the place tidy. Similarly, for the smokers in the space, an old bowl or cup makes a way better ashtray than the top of a P.A. speaker.

Commit To A Schedule
Ever arrived at your space for practice only to find another band mid-set? Even worse, mid-set using your Blues DeVille? It's a feeling that's probably similar to how a beaver feels when he leaves his dam in winter to forage only to come back and find a younger, more attractive beaver living in his den.
Unlike our beaver friend, however, 21st century musicians have smartphones to help avoid these awkward scenarios. Try using a shared Google Calendar or scheduling app to make sure the entire population of the space is crystal clear about when their allotted times fall. For those random strokes of rock-spiration, maintain a group text you can ping to make sure no one's in the space when you feel like dropping by. Even if someone is using it at that very moment, chances are you can find out when it will be free later in the day. Who knows, maybe they'll want to jam when you get there. Bam. New powerviolence duo.
Be Mindful Of Lingering Odors
I admit, this particular guideline may be a bit too closely based on my own recent experiences, but the fact remains that small, confined spaces full of half empty beer cans and sweaty citizens of a local rock scene tend to smell quite bad. When the heat of summer and the heat of tube amps combine with the lingering cigarette butts (...and other smokables), the result can be more intense than those lyrics you wrote about your last break up.
As mentioned above, you should always have a couples minutes to clean out ashtrays and toss those empty bags of Fritos and wounded soldiers. Make a point to stand with the door open for a few minutes at the end of a session or when you feel like taking a break. Every little bit of circulation helps. While it's not a cure-all, it never hurts to also have an emergency supply of Febreeze or incense somewhere in the room.
Well, there you have it. As is usually the case with posts like this, I'm willing to bet that you all have your share of practice space horror stories and adages to share. Let's hear about them in the comments below.