I assume that when you say "voters" you mean people in general who are not public officials. I assume you are asking if people ought to do more than just vote. I would say that they should if it is at all possible.
The reason for this is that voting is a very "blunt instrument" for telling government what you want. If you voted for Pres. Obama in 2008, what did it mean? Did it mean you hated Sen. McCain? That you wanted to punish the Republicans for Pres. Bush? That you agreed with what Obama said? If so, which thing? We can't know any of this stuff. By participating more actively, a voter can clarify the meaning of their vote.
So I would say that voters should get involved. They should join interest groups to lobby for their interests. They should contact their representatives to air their views on important issues. They should write letters to the editors of newspapers. By doing these things, they can let people know what they really think -- something that just voting does not achieve.