The failure of the pilot of N123WA and the failure of both pilots of N301NL to adequately insure visual separation between their aircraft and other aircraft in the landing pattern, resulting in a runway collision. Factors contributing to the accident were the pilots of both aircraft not using the correct UNICOM/CTAF frequency, and the pilot of N123WA executing a landing approach that conflicted with the traffic pattern entry recommended by the Aeronautical Information Manual for airports without operating control towers.