Getting seals is easy. Follow this guide.

1) Go to FFXIclopedia.com
2) Look up the seals you need and what monster drops the most.
3) Get a team of 4-6 people. All the jobs to cover all blue triggers and THF for Treasure Hunter if you want.
4) Get the blue weakness trigger.
5) Repeat until all seals are obtained.

If you sit around and wait for someone else to start a seal run, you're only wasting time. Gaining seals for my DRK was 5x faster after I took my own initiative.