A gentleman posted in /r/asktrp with a question -- he is about to begin a new job in which he is the only male in a group of twenty-five females. If that made your asshole pucker in terror, good: you're right to be cautious. This list was written for that man, but the rules apply to any man forced to work alongside women.

Follow these rules to maximize harmony, reduce needless stress, and survive disaster. (6th critical point added by /u/cyralea)

1. Never, ever, take sides. Women will approach you and complain about each other; it's what they do. Listen, empathize, and never, under any circumstances, take one woman's side.
2. Get used to refusing requests for help. Every job I've ever had with females, they were constantly trying to offload their basic job description onto the males. In other words, they were always asking for help with shit they should be able to handle. As the lone male, this will be amplified times a hundred for you. Just say no to shit.
3. Do not fuck any of them. These women are off-limits for fucking. The simple rule, of "don't shit where you eat," is quadruply appropriate for you. Women can't keep secrets. If you bang one of them, the rest will know within a day or two. Guaranteed. Don't do it.
4. Don't be too effective. Women generally don't work very well, and they constantly require group validation. You put these two things together, and what you get is an environment in which everybody is aware of how hard everybody else is working. The level of work of each woman is well-calibrated to both: not get fired, and not make anyone else look bad. In a male environment, everyone is trying to get ahead. In a female environment, everyone is trying not to piss everyone else off. Figure out how hard the top 5 women work, and work that hard. But NO HARDER! (Edit: Read the culture, go with the flow, and don't make a woman look bad. It comes down to culture. If your female coworkers are effective and low-drama, by all means -- kick ass. Just be wary. Exclusively-female workplaces have a tendency to devolve into... cattiness, which creates loafing. The presence of a single male changes that. If you were to enter a catty, ineffective group of females, bringing a male ass-kicking attitude, it would send shockwaves of surprise and distress through the females. Seriously -- I cannot overstate how nutty it gets without any males. Just read the article Read from halfway.
5. Don't play favorites; conduct yourself as a loner. Women are hypersensitive to politics. Groups of women will try to enlist you as a beta orbiter constantly. Stay aloof. You're the rooster in the henhouse; you're the adult on the playground. Just hold yourself to a good standard of behavior, and stay out of muck of female relationships. Women don't need a valid reason to hate you. It could be as simple as, "you always sit with those women at lunch, and I don't like them. So I don't like you. No promotion." Sit alone, eat alone, keep to yourself. Better to be the enigmatic loner than Cathy's male bitch for all the other bitches to hate.
6. Never confide in these women. They will likely question you and pry into your life under the seemingly innocent guise of friendly banter. Don't fall for this. The more they learn about you, the more they have leverage to potentially use against you. Keep your conversations light and professional, but most importantly fact-free as it pertains to any aspect of your personal life. Any given one of them might be friendly today, but maybe tomorrow she is catching a vibe from the other ladies that you're untrustworthy. Her feels won't let her rebuke them. Suddenly all the things you confided to her because she seemed like a decent person go out the window.

That's it; good luck, brothers.

Edit: we're getting some confusion about #4. That advice is for a lone man in an otherwise all-female environment. In that situation, the women's level of effort is calibrated to each other, which is typically way lower than what they're capable of. In that situation, if you did your best, you'd embarrass all the women. In a normal, mixed-gender environment, that's not a concern; just do your best.

2nd edit: for some epic lulz, see what happened to an all-female TV company.]

3rd edit: Fun story in support of #4. In the past, I made acquaintance with a veteran aerobics instructor in her 50's. She was a cool gal, very direct, with an old-school midwestern attitude. She was a great trainer because she was encouraging, but called you on your bullshit.

She invited me to attend her aerobics class for free. So I went. Fun, decent cardio. Interesting thing was, I was the only male in the room. So I fuckin' stepped up and gave it 100%.

Chit-chatting afterwards, she mentioned something to me. "I'm glad you're here. It helps to have a guy here."

Pause. Whoa. Interesting... "What do you mean?"

"Well, if there's no guy in the room, they all slack! And they complain endlessly! GOD.. it's so irritating! .... But with just one guy here, not a peep."