"do's and don'ts"

[Torchwatch]

Wear something that you feel comfortable in and that won't end up dangling around your ankles when you dive in or kick off the sides.
When you start swimming in a new pool wear something fairly conservative so that if you are the only male in swim briefs they won't make you stand out as a freak. As you get used to a pool start wearing brighter colours and patterns if you feel they will be accepted. Swimming is sporty and sensuous and you should try to reflect that in what you choose wear when you swim.
In Europe swim briefs are about 2" long at the side, while Americans seem to prefer 3" sides. A swim suit with 1" sides is considered a swim bikini and should only be worn in a public pool if you are confident that you will be accepted in it, after wearing a 2" swim brief.
The front of your swim briefs will display a bulge, a lined suit front will smooth over your bulge so that it will not catch the eye. Unlined, pouched or transparent suits will draw the eye to this area. Try to balance how many eyes you catch against causing offense and being asked to leave the pool. You will have to learn how the other swimmers and Lifeguards in your pool react before taking things to the limit, but gently push the envelope and see if the others object or join you by converting to speedos themselves.
Have fun, collect a few speedos that you like but don't get banned from the pool.
The briefs you can't wear at the pool can be fun at home or on a quiet beach.