If your local parties have been putting the ground-work in, they should now have accurate “Voter ID” lists. Residents will fall into the following categories:
Never vote – so don’t waste your time
Always vote for the other side – again, don’t waste your time
Always vote for your side – so encourage them to actually vote
Marginal support/floating – worth talking to, to persuade them to vote for you
This might sound a bit cynical, but very few people are members of political parties these days, so it’s essential to use marketing techniques to make best use of limited resources.