The standard line issued by safer sex advocates is to always use condoms
So your first decision will be how many men you wish to entertain. The specifics are likely to be determined by whether you elect to use people you know, recruit random participants, how the gang bang is constructed (as a stand alone event or part of a party or other gathering), etc. If you have a circle of friends from which you can draw a dozen participants, then you may elect to have a larger bang.
Once you’ve had your first experience, you may wish to move on to larger groups, or perhaps those involving alternative power differentials, role play (the school cheerleader is taken out back and “gang raped” by the school basketball team, for example), bondage scenarios and the like.
One of the primary issues with a larger group of bangers is the potential for those not actively engaged in sex getting bored (and thus, the need for fluffers)
You’ll need to make a decision about whether or not to require condoms for penetration. The reality of a gang bang, however, is such that it is often more practical to disabuse everyone of having to worry about those. There are several reasons for this.
First, if the guys are rotating among orifices, you’re going to end up with condoms in your mouth. Some don’t mind that, but many people have an aversion to the taste of latex (or the materials used in non-latex condoms as well). Condoms also introduce more friction into the process and over a two-to-four hour GB, that’s going to wear out your naughty bits a bit more than bare skin, even with lube.
One of the reasons some women enjoy a gang bang is being filled with and/or drenched in semen – a bukkake experience as it were. Obviously, being filled with semen isn’t possible when using condoms (condoms can be removed prior to ejaculating on the center’s face or body, of course).
Risk is inherent in all sexual activities, so you’ll need to decide if that risk is low enough for you and the participants in the gang bang
If you’re going to allow participants to fuck you without condoms, they will need to be tested and be prepared to provide results of those tests when they show up. You, too, will need to be tested and have your results available for inspection. I had my bangers do two sets of tests – one 30 days out and one within 7-10 of the bang itself. Keep in mind that even the best testing regimens cannot detect the presence of some diseases (for example, HPV in men), so everyone having negative tests does not preclude someone from actually having a contagious disease.
Even if you elect to dispense with the condoms, you should still allow those who wish to use them to do so for their additional info own safety and peace of mind.
Organizing a gang bang of any size can be a daunting task, especially if you have to get into renting space, finding fluffers (how many people know where to go to find those? They’re not in the Yellow Pages!), meeting prospective bangers, etc. So you are highly encouraged to hire/use the services of a Gang Bang Coordinator. This person will take care of all of the arrangements, to include finding and screening participants, securing space, setting up the room, and so forth. There’s a lot more to that than you might imagine, and it will allow you to insulate yourself from having to deal with screening potential bangers (which has several advantages).