The best way would be to distribute Electoral Votes proportionally by county.
The number of electors in each state is equal to the number of members of Congress to which the state is entitled,[4] while the Twenty-third Amendment has granted the District of Columbia with the minimum number of electors permissible for a state, which is currently three. In total, there are 538 electors, based on there being 435 representatives and 100 senators, plus the three electors from the District of Columbia. - Wikipedia