Well not being completely paranoid about all Japanese-Americans being spies was one thing. The government could have reinforced and publicized the all Japanese unit they had in Europe (who later became the most decorated unit in all of American military history) so the American people wouldn't have been so quick to assume their Japanese neighbor was out to get them.
I think they could have used the war time propaganda to positively help the Japanese-Americans. Instead they used it to vilify the Jap Army which I can understand, for a soldier it is easier to kill something that is "dehumanized" but they could have used positive propaganda - like "This Japanese-American family is doing their part to support the war buying war bonds!" or something just as corny.