This entry is mainly aimed at women, as they are much more at risk of catching HIV than men are during penile-vaginal intercourse. This is because more virus carrying fluid is transmitted into the woman than the man, making her more vulnerable to catching HIV. Also, through correct use of a condom pregnancy risks are considerably lowered, and women are in a good position to do something about it by incorporating it into lovemaking more naturally than the 'hang-on-a-minute' fumble that can momentarily put even the most aroused male off their stride.
How to Go about It
Assuming you are right handed, your right hand is 'safe' and used only for touching your self, and your left hand is used for touching him. This keeps down the risk of fluid transmission by hand. Keep the penis rhythm going with left hand, while finding a condom with the right from wherever you may have dropped it.
Carefully rip condom packet open with teeth, (emphasis must be placed on 'carefully', as any small tears or holes caused will render this advice useless).
Remove condom gently with lips or 'safe' hand.
Say 'ooh' and place the condom teat between your lips sucking slightly - this isn't to show what a good time you're having - though you shouldn't be doing it if you're not - it's to get the positioning right! This may look a bit silly, so practising it is a good idea. You should be able to feel whether the condom is right side out or not by the way it unrolls very slightly as you suck it against your lips - learn what this feels like and you can do it in the dark.
This is the tricky bit. Let go of the penis and put the first two fingers of each hand inside the rim of the condom. Suck gently to anchor. Stretch condom open and move forwards pressing end of penis against the bit held by your suck and then roll down simply by pulling your fingers away from you. Suck a bit harder to anchor it as you do this, so it doesn't just fly away.
Hold condom on at base of rubber with 'safe' hand so your lips only ever touch your clean fingers.
Mistakes You May Make
Getting it inside out. It won't unroll correctly, plus the fingers that you've used to touch his penis with will be rubbing down the side of the condom that's going in you, which defeats the object.
Stretching the condom too much or with your fingers at an angle can break through the condom, or make it weaker to break later. Try and use the flats of your fingers. Sharp or long fingernails are hazardous for obvious reasons, and fingernails should be checked for sharp edges beforehand.
Sucking too hard during the roll down results in a huge air bubble at the end or a total balloon effect. The first isn't safe sex, and the second will totally destroy the moment!
For the More Advanced
When you've recovered from accidentally inhaling a condom and don't get air bubbles any more you could try following the roll down immediately with your mouth... not only does this feel great but many men won't know you've put one on if the rest of it was smooth and quick. This avoids any discussion, intimidation or off-putting shift of consciousness or break in the rhythm of the moment. Because the condom is anchored due to the suck pressed against the penis-end it is possible to unroll on a half-erect, or even on a limp penis, then suck until he is erect. You have to be very careful - unroll down to the base of the penis and as he gets harder. Your 'safe' fingers against the unrolled rim will give a base to unroll against. This is difficult to describe but rest assured, it does work.
If you or your partner object to the smell or taste of condoms, then you will find flavoured condoms widely available. The taste of these is similar to the synthetic flavours you find in sweets, and remarkably similar to some bubblegum!