More than a third of all privately held companies in America are owned by women. Thaey employ about 18 million people. But when the public-relations executives Caitlin Friedman and Kimberly Yorio decided to form their own company, they couldn’t find any guides to help them. So they wrote their own, titled The Girl’s Guide to Starting Your Own Business (HarperResource).

It suggests how to test your self-employment options and learn where your talents really lie, and it gives advice for working from home (including setting a schedule, getting out once a day, having dedicated business phone lines and not lying on the couch). It also suggests how to decide if you want a partner, gives the basics of renting office space and offers financial tips and ways to look for new hires. (The authors advise not to employ friends, neighbors, a former boss or a former assistant – and to never confide in employees or clients.)

Finally, manners go a long way. Don’t put criticisms in e-mails, and be sure to send real notes, on paper to thank people for help or referrals – which is good advice for all of us.