My first run-through has been very much a ~learning experience~.... when I get around to doing it "right", one thing I definitely want to do is assign "uniforms" to my settlers so that guards are dressed lke so, and merchants are dressed like so, and farmers are dressed like so.
As it is, it is hard for me to tell whether I have already assigned a settler to a task or if he's new to the community and has no job. Sometimes I'll grab a settler and say, guard this station and then my food total drops and I realize that that was one of my farmers... so then I have to go find a settler to take up farming.