• Whether or not you've ever had intercourse with a guy, you still need regular pap smears. HPV can be transmitted from genital-to-genital contact, even if a penis isn't involved, and may hitch a ride on your fingers or sex toys. If your gyno doesn't seem attuned to your concerns and needs, find another. Some of my patients didn't seek care for years after facing prejudice from a doctor. Don't let someone else's bias impact your health care.
• Speaking of toys, it's best not to share. Any bodily fluids can transmit infection; keep your toys clean, but keep them to yourself.
• While the risks of sexually transmitting HIV between women are very low, and very few women are known to have become infected with the virus through sexual activity with a woman, it is possible. There's increased risk of transmission if a woman has cuts or cold sores in her mouth, or if her partner receiving oral sex has genital sores or is menstruating. 
• Make oral sex safer by using a barrier to prevent any vaginal fluid or blood from getting into your mouth. While you can buy dental dams for this specific purpose, a condom cut open or even a piece of Saran Wrap can be used in a pinch.
• Any sexual activity that can lead to cuts or breaks in the lining of the vagina or anus is risky. So if you engage in aggressive play like fisting, make sure you use plenty of lube and take your time.

I'll directly address particular STDs in my next post.  Have any of you felt safer by only having sex with women?