1) Read Sheryl Sandberg's 'Lean In' or find another way to learn about how direct, indirect and unconscious bias impact on women in the workplace. Respect the evidence. We are not making this up.
2) Be aware of your own unconscious bias in your interactions with women and men at work. Does that bright young man really have the track record to back-up his self-confidence? Are you giving the woman chair the respect she deserves? We are all prone to this, men and women unconsciously judge women more harshly than men at work. Being conscious that we are doing it is a good starting point to overcome it.
4) Make sure maternity, paternity and carers leave are treated as normal costs of business and have well developed systems for implementing them. Do not make a big deal if someone needs time off to care for children or parents. If someone is worried about a sick kid and then you put them under extra pressure at work they are unlikely to perform at their best.
5) If you have children, take your full entitlement of paternity leave. Don't make a song and dance if you need to take time off work to pull your weight taking care of your kids. You are a parent, you are taking care of your children not giving CPR to the Prime Minister. On the rare occasions when childcare plans fall through and you need to bring the kids to the office, do not expect your subordinates to take care of them. That is just rude.
6) Always check that you haven't missed out any women when short listing for jobs, arranging speakers for conferences, pulling together a team for a high profile project or anything else you do at work. If you have less than 30% women on your list you have might have missed someone out. This is not because you are sexist, it is just how unconscious bias works. I have found myself in this position, and doing the quick check of 'are there any talented women I've forgotten' often reveals very important people who I have inadvertently overlooked. Putting aside debates about enforcing targets on committees and short lists, noticing that you don't have enough women on your list can be a good way to double check that your selection criteria are working properly.
7) Mentor a woman or, even better, sponsor one. Mentors are very important for women who might not naturally fit into the 'old boys network' and need extra support in learning how things really work in the workplace. Sponsors who take on particularly talented women and actively look to create opportunities for them to develop are even better.
8) Always provide a microphone for anyone giving a speech or presentation. Women's voices don't carry as well as men, which means we might literally be straining to be heard.
9) Don't be afraid of affirmative action. If you really are faced with two mythically equal candidates and one is a black woman and the other is a white man, the black woman will undoubtedly be the more talented and hard working of the two. The man will have benefited along the way from little boosts of positive unconscious bias and may be riding higher on self-confidence than track record. The woman has made it to that point despite the barriers of sexism and racism. Affirmative action is your friend.
10) Check your privilege. You have probably benefited along the way from being a man in a man's world. Of course you work hard but there are big and small benefits of being a man that have worked in your favour. At the very least you haven't wasted any of your energy dealing with the frustrations and real obstacles of sexism which you most certainly would have faced had you been born XX. Admit your 'luck', especially when you might be tempted to judge women at work for being a bit uptight, too bossy, or 'not quite the right fit' for the team.