I have always found that door knocking has been the most effective way of building a round. I am building a round from scratch in Ireland, and am still canvassing to fill in the gaps.
Fortunately, for me, I have no hangups about knocking doors. I am polite, friendly, relaxed and try to make the householder feel the same way.
Is it tiring? At times, yes, but then if we want something badly enough we will look beyond that to the reward that repays the effort.
John