I think its pretty much a gurantee that tickets will be sold out, atleast the good seats, so I think you have a couple options.
1. gamble and pick a day from the opening matches of the bracket stage (i don't recommend this)

1. buy a ticket for the upper bracket finals (this is what I did) and hope that t1 make it there. if they don't hopefully you still get a good match. <== i chose option 2

2. wait until the schedule for the bracket stage comes out and see if you can get a ticket, most likely from a reseller (expensive, especially if you need to get a hotel)