Channel 12 is probably not one that you would want to communicate on.
Here is a list of vhf channels and what they are used for.
http://www.boatsafe.com/nauticalknowhow/vhf.htm
In normal circumstances (provided there is no emergency) you would want to used a non-commercial channel. Most guys use something between 68-72 for normal communications. Hope that helps.
Also be advised channel 16 is the emergency channel that would summon coast guard, as channel 9 would be another option in case of emergency if no response on 16.