1. Go to Timeless Isle and gear up your character.
2. Do some raids in Raid Finder.
3. Kill world bosses for gear (use new raid browser to quickly find groups).
4. Every single faction on Pandaria gives you a mount at exalted so do dailies to get them.
5. Check out Scenarios and Heroic Scenarios.
6. Complete some Challenge mode dungeos for cool transmog items.
7. Check out Pet Battles.
8. Check out new solo PvE arena (Brawler's guild).
9. Raise your professions.
10. When you're geared enough try out Flexible, Normal and Heroic difficulty raids.
11. And ofc don't forget about PvP