[edit] Steps

Know who wanted it more. If it was you, try to figure out how you really feel about the person. You might have confused lust with love or might have been on an emotional roller coaster at the time.
Figure out if the person wants to talk to you. If they look your way frequently, chances are they need to talk as badly as you do. This can be confusing too, since they could be in an awkward position, but start a conversation with them either way to loosen the tension.
Go up to them and ask how they are doing. This is a good ice breaker and will get a conversation starting between the two of you. Ask simple questions like this to keep it going and not have dead silence. If its still awkward, say goodbye and try another time. Some time apart can help this. Try again another time.
Learn from your past. Don't come on too strongly to any of your friends. Even if you think its just flirting, they may not.
Acknowledge what happened, not doing so would be rude. Either person should call (not email or text) within 24-48 hours, especially if you wish to see more of them.

[edit] Tips

Avoid all the problems by having a post-hook-up conversation. Be polite and gracious for the physical attention, but explain your wants clearly and directly.
Treat the person the same as you did pre-hook up. If emotions are changing, talk to them about how you feel and see if they feel the same way.
If you need to, tell one good friend about it. Make sure it is somebody you trust, however, otherwise your secret may get out. Sex is a private matter and not for public knowledge.
If alcohol or poor judgment was involved 'it is necessary' to contact the person within 24 hours to discuss what happened. Even though it is awkward you should establish upfront what occurred and agree on how to move forward. (Pretend it never happened, be friends, be friends with benefits, etc. so there is no question.)
If you are dating someone else you should be clear about it and establish if you will or won't continue to see each other.

Do not tell everyone you know. The situation was probably different than you made it out to be. You don't want the other person involved to hear juicy details about their hook up that just aren't true.
Do not assume that you two are a couple or anything similar. Wait until you talk to them to decide this.
Avoid hooking up with your friends. Unless you have made it clear you want a relationship or you still want to be friends and you are comfortable with talking about it to them, keep away from them.