I am wondering myself. Here are my ideas:
- kayak.com is very nice for searching cheap flights
- book your ticket at least 21 days before the flight. The earlier the better.
- maybe sign up for frequent flier program? I know American Airlines credit card gives free ticket and you can earn miles by using the card, flying, renting a car, staying in hotel.
- If you know someone who also has an interview on the same date, you share the room.
anything else?