Use cooldowns when they are needed, not when they are up.
1. Rampant - don't use it before the fight, wait until there is a stable incoming damage, so it will actually become useful.
2. Fight or Flight - save it for boss if you have an overgeared dps in team.
3. Convalescence - don't use it when you do not need healing (like from start or during multi-pulls) or when healer is dead.
4. Don't use Hallowed Ground at start - let healer use Benediction/Lustrate first, save it for when it is really needed.
5. Use Flash - it is a good cooldown that lets your team and you to dodge special boss skills.
6. Get Foresight from the Marauder - it's just like rampant, but 30s longer cd.
7. Overpower more (for marauders) - no reason not to.