Eeee, this node is pretty huge and usually editors/gods no like huge nodes. Anyways, I think
ApoxyButt might have the most informative writeup with respect to the node title, but here are some additional factors influencing your urinal choice and etiquette:
1. Liquids belong IN the urinal
Well truth be told, some people have poor aim and you obviously don't want piss on your shoes. Urinals at pubs seem to have this problem. Gee I wonder why...
2. Pubes
It's quite engrossing when you see hairs all over the rim of the urinal and wonder who they used to belong to. Well maybe you don't, but obviously you should choose the one with the least amount of pubes and if you're courteous, please keep your pubes to yourself.
3. Keep your pants on
Little children oftenly do this and I've been tempted to do this due to extreme drunkenness, but you should always keep your pants on while urinating. Simply unzip yer fly and you'll be fine. If you do however choose to drop your pants to the floor, exposing your bare naked ass. All I can say is be prepared for something to happen.
4. Control your anxiety
This is from personal experience. Try not to be too anxious in whipping out your little buddy. Make sure that you are within range of the urinal before taking out instrument of evacuation or evacuation for that matter (rule #1). Otherwise, you might give the wrong idea to people disobeying rule #3.