Warhammer Online: Nordenwatch - Specific Strategies

If you play the scenario enough, you will indeed develop tactics that work best for you. But in general, this works for the various archetypes:

Get to the flag and fight on the flag.

That is your main role in almost every engagement. If fighting near a captured objective, you can then assist DPS in taking down the opponent. If your objective is in jeopardy, once again you should fight on the flag to prevent its capture. If you have enough people holding the flag, it may occasionally be a good idea to stand with your own team's support, guard a healer, and help them stay alive.

When skirmishing, putting guard on a strong DPS player on your team can help them stay alive longer to really crush the enemy (and see them driven before you!).

If your team has no tanks, get to the flag and fight on the flag. If you have tanks, help take down healers and DPS of the enemy. When not fighting for an objective, stay with your team and work to drop the other team's support as quickly as possible. Work together and assist with other DPS players.

If your team has no other melees, bad news... you need to fight on the flag. Sorry. Otherwise, work together with your other DPS to drop their healers and DPS.

The nature of stealth in Warhammer Online is such that scouting is really not a significant role for stealth players. 30 seconds of AP draining stealth does not give you much opportunity to scout the enemy. But there are occasional opportunities for scouting, and you should be on the lookout for them.

If your DPS is high enough, you can occasionally sneak back into the enemy's healers and drop one fast. This is always very helpful to your team.

Get in a good position that limits the line of sight of opposing ranged DPS, and work with other DPS to crush the enemy's healers and DPS. Failure to assist with other DPS can result in a lot of wasted damage that gets healed away. You want to drop people as fast as possible and then move onto the next.

Remember that staying alive usually results in more overall DPS than going berserk and dying soon after. Backing off so HoTs can tick on you is only a brief interruption of your DPS. Blasting away until you die is a much longer loss of DPS as you must wait to respawn and runback (resurrection is rare in Tier 1 since it is learned at level 10).

Keep those tanks (or melee) alive who are fighting on the flag. If they die, your enemy will capture the objective. Keep yourself alive! Many healers forget to heal themselves. If there are DPS who make a habit of killing people attacking you, keep them alive! They are clearly smart players who will help you survive.