Cunnilingus is the act of performing oral sex on a woman. One way to make cunnilingus safer is to use a barrier to cover the woman’s vulva. A barrier can be a dental dam, a condom slit open down one side and unrolled, or even a piece of non-microwaveable plastic wrap. But, whatever you use, just make certain not to accidentally flip it over mid-act.
Fellatio (a blow job) is the act of performing oral sex on a man. Oral sex isn't safe sex, but you can make a blow job safer by putting a condom on your partner after he has become physically aroused, but before ejaculation. It is possible to put a condom on someone using your mouth, but it requires practice. Fortunately, it’s not that difficult to find a willing voluntee... or a banana.
To make intercourse, either with a penis or with a sex toy, safer, use a condom. Male condoms are easier to use, but some people prefer female condoms for vaginal intercourse since they cover more of the surface of the vulva and as such may provide some additional protection. However, it’s important to be careful since it is easy to use a female condom incorrectly. Detailed instructions for how to use a male condom and how to use a female condom can be found at the links. It is also extremely important to use a condom-safe water or silicone based lubricant during intercourse. Proper lubrication not only makes it less likely that a condom will break, or delicate tissues will be damaged, it makes sex more fun!
Digital sex doesn’t mean looking at pornography on your computer. It means using your fingers to penetrate your partner. Using gloves, or finger cots (essentially little condoms for your fingers), can reduce your risk of being exposed to any viruses or bacteria that are in your partner’s secretions. Just as with condoms, you should always switch gloves if you move from penetrating the vagina to the anus, or vice versa.
Rimming, or oral-anal contact carries any number of potential health hazards. There is a risk of infection not just from STDs but also from intestinal bacteria. It is important to use a dental dam when performing oral-anal contact to keep yourself safe. If you don’t want to buy a dental dam, they can be made by cutting a condom down one side and unrolling it, from a latex glove, or even from non-microwaveable plastic wrap.