Plan the schedule
Mark the date of showing at your calendar so that you can schedule your efforts for the availability of the tickets respectively. Note that the good seats are always sold first. Therefore it's essential that you go out and buy the tickets as soon as they're available for sale.
Contact theatre administration
You can also call the ticket sales office for inquiring the availability of the seats. The websites often tend to reserve the seats in an order and might not deliver you the seat that you wanted to. While an agent might be able to find seats for the showing, but delivering the one of your choice. However, you buying the tickets for yourself can definitely promise yourself the experience that you desired, but booking the seats of your preference.
Consult your travel agent regarding the availability of the tickets. Your best shot would be contacting a ticket-broker for the tickets, as he can not only ensure you the availability of the tickets, but also provide you with a seat of your choice for the an expensive price.
Say updated with the website
The event or theatre's web portal is an easier source to access for the interested public, as they won't have to visit the theatre over and over again regarding the availability of the tickets. The website is also a platform for the sales of tickets, and if you keep a close eye by staying update through their website, you can just reserve yourself the right seats for yourself.
Listen to the radio
Check out over the radio, as they might be giving away free tickets while hosting their shows. You might have a good chance of getting yourself a ticket than looking for it from another buyer who has acquired a ticket and is willing to sell it because of some certain reason.
Benefit from your credit card
Try buying tickets using your credit card, as sometimes banks and other financial entities have booked the tickets in the theatre prior to their sale, knowing that their clients might be looking for best buys. Don't hesitate to use your credit card for purchasing the tickets as it's a safe and easy medium to do so. Moreover, you wouldn't need to wait in long lines at the ticket counters just to get yourselves information regarding the tickets, rather than buying them instead.