"The Nation that makes a great distinction between its scholars and its warriors will have its thinking done by cowards and its fighting done by fools."
~Thucydides
"Paintball is a sport in which players eliminate opponents from play by hitting them with pellets containing a paint like substance (referred to as a "paintball") usually shot from a carbon dioxide or compressed-gas powered paintball gun (or marker)." -Wikipedia
Paintballs will typically sting only for a brief moment, if at all. Generally speaking, a player's adrenalin is usually so ramped up during play that they may not even realize they've been hit. Wearing loose fitting clothes and some sort of neck protection will keep any discomfort to a minimum.
As with any sport, certain percautions need to be taken to ensure safety. Adequate protection must be worn at all times and players should be aware of their surroundings. Statistically speaking, paintball generally results in far fewer injuries requiring a trip to the emergency room than football, basketball or even golf.
Standard games of paintball typically last between 20 and 30 minutes and will usually only have one objective. Single elimination is often the norm.
Scenario games generally have more to offer players in regards to storyline and diversity. "Almost all scenario games are 'big game' style events, designed with hundreds or thousands of players involved. The games offer extended play times, anywhere from 6 to 48 hours. Players that are eliminated with a paintball hit may return to the game after a pre-set period of time, giving players a chance to be part of the action throughout the event.
Scenario games are almost always objective-driven in regards to
scoring. Each team must complete a series of missions to
score points.
These may range from simple 'capture the flag at this location' missions, to
elaborate missions involving props, multiple locations, interactive
non-player characters and more." -Wikipedia
Will the paint wash out of my clothes?
Typically the answer to that is yes, although if left untreated for extended periods of time, the clothing may stain. A good rule of thumb is to wear clothing that you won't mind getting a bit dirty.
Do I have to be on a team to play paintball?
Not at all. In fact, walk-on players are highly encouraged. Formal teams will often welcome the opportunity to add these players to their ranks for the day to help plug security gaps in the defenses, run scouting missions or assist in massive attacks. It's certainly not necessary to work with any player or team on the field, but most players will find that in doing so, their enjoyment of the game is increased.