Originally Posted by ChiliColdBlood

One thing I haven't seen mentioned is Pre-sales. If a show has a presale, treat it as a normal onsale time. Usually by the time the tickets go on sale to the public the best ones have already been sold during the presale. Sometimes getting the password is as simple as being signed up on the band's website (I've done this for the Foo Fighters and Nine Inch Nails). Other times, the password isn't as widely available. For the Unwigged & Unplugged (Spinal Tap, kinda) show in Toronto, I did a bunch of google searches for their presale passwords and tried different ones that they've had for previous shows. Eventually, one of them worked and I got good seats.

Ticketrush.com is affiliated with Live Nation and will give you free presale passwords to a ton of shows as long as you sign up. I don't really get why this site exists but you may as well take advantage of it.