As far as the USA is concerned, the activities of JW's are not considered soliciting. There's been court cases establishing this. "No soliciting signs" or "no salesman" signs or whatever, technically do not apply.
No Trespassing (or I suppose NO JW) signs are definitely the way to go. Now I think 'most' JWs avoid homes with them (YMMV) because if a householder presses charges or whatever (which they can) the WT will not back that JW in court.