There are 5 WG quests available, and they are on a 4 day soft reset, with a hard reset every Tuesday at 3AM server time - this means you can get them done twice per week - if you do them shortly after the hard reset, and again 4 days after that.

Each quest rewards 3723 honor, 10 Stone Keeper's Shards and 13g23s

Two of the quests can be done in between battles:

Slay them all! (H) / No mercy for the Merciless (A)
Requires you to kill 10 players or guards of the opposite faction

Fueling the Demolishers (H & A) - Fire Elementals
Bones and Arrows (H & A) - Shadow Elementals
Healing with Roses (H) / A Rare Herb (A) - Life Elementals
Jinxing the Walls (H) / Warding the Walls (H) / Warding the Warriors (A) - Water Elementals
These are gathering quests that require you to collect 10 quest items from killing the elementals in various areas of Wintergrasp. Things to note:
- The quest randomly changes every day, however they all share the same reset timer.
- 100% drop rate and everyone in the raid can loot from the corpses if they are in the area at the time of the kill.
- Killing opposing faction players in the quest area will yield 5 quest items, so two player kills are enough to finish the quest (you must loot the corpse before the player rezzes up at the spirit healer though, otherwise the corpse becomes non-lootable).
- Both horde and alliance quests will be set to the same area (WG is for pvp after all )

The remaining 3 quests can only be completed during the battle:

Victory in Wintergrasp (H & A)
Completed when your faction wins a Wintergrasp battle. This quest can only be picked up after a battle has started.

Defend the Siege (H & A) / Stop the Siege (H & A)
Defend the Siege is available before an Offensive battle (i.e. your faction is attacking the keep) and simply requires you to be in the same area when 3 siege vehicles break through a wall.
Stop the Siege is available before a Defensive battle and requires you or someone in your raid kills 3 siege vehicles.

Toppling the Towers (H) / Southern Sabotage (A)
This quest can only be picked up after a Defensive battle begins and requires you or someone in your raid to destroy a southern tower. You can be anywhere in Wintergrasp when the tower is destroyed and still get gredit.

Losing a battle in Wintergrasp will yield 1 x Wintergrasp Mark of Honor

Winning a battle in Wintergrasp will yield:
1 x Wintergrasp Mark of Honor for Rank 1 (Recruit)
2 x Wintergrasp Mark of Honor for Rank 2 (Corporal)
3 x Wintergrasp Mark of Honor for Rank 3 (Lieutenant)
You gain rank from killing opposing faction players or being in the same area when an opposing faction player is killed.

30 Stone Keeper's Shards or 9 Wintergrasp Marks of Honor can be redeemed for Wintergrasp Commendations, which reward 2000 honor when used and are Account Bound (i.e. you can send them to other toons on your account).

I use this basic strategy which offers a good mix of honor, gold and emblems:
1. Do Wintergrasp whenever it's up.
2. Try to complete all the WG quests twice per week (worth 37K honor in total, not including honor from turning in Shards & Marks)
3. If your faction controls WG, run heroics (since you'll also get Stone Keeper's Shards from isntance bosses).
4. If the opposing faction controls WG, run dailies

Hope this helps...

Cheers,
S.