Research your airline. Most airlines follow similar procedures when handling standby flights, however, you don't want to encounter any unpleasant surprises at the last minute. Call or check online to verify before purchasing your ticket.
Phone ahead. Your chance of landing on an earlier flight depends on the availability of seats on board. Before you head to the airport, inquire with your airline about how many empty seats a prospective flight has, to know if you have a good chance of making it or not. Airlines are constantly booking and releasing tickets all the way up until takeoff, so it's best to call and inquire right before you plan on heading to the airport.
Head to the airport. Once arriving, speak to the person at the ticket counter to check in and to place your name on the standby list. This must be done in person.
Wait near the gate. If your name is called and you aren't present, your spot will go to someone else on the standby list. Make sure you are nearby and eagerly waiting to board.