Stormwind Guard collection
An Alliance player cannot actually join the Stormwind Guard, but they can look the part for roleplay purposes.
NOTE: With the introduction of the Dwarven Bunker in Warlords of Draenor, you will be able to buy matching transmog pieces in the Stormwind Set to look like a member of the Stormwind Guard.
Required
- A plate wearing class, like a Paladin or a Warrior.
- A death knight could be used, however, death knights cannot wield a shield as a guard does.
- That class has to be at least level 55, due to the level requirements of the armor needed.
- That even matters if you intend to transmog the armor. You cannot transmog armor you cannot equip.
Race
The Stormwind guards are all humans, so if you want to really look the part and even be mistaken for the NPC, you'll need a human. You could also opt to be worgen, who can transform into humans. You don't have to be, though - you could just be the first non-human in the job!
Armor
You can wear these pieces or you can transmog your armor to look it. It doesn't matter. If you're at level cap just remember to change before raiding!
The easier parts
- Tabard: No tabard is an exact match. You'll need a
[Stormwind Tabard], available from Captain Lancy Revshon in Stormwind for a mere 10
. The PvP tabards can work, too, but require honor to buy. - Almost all armor: Pick up the full set of Imperial Plate, which requires level 40. You can buy it in the Auction House or have any blacksmith make it - the plans are learned from the blacksmithing trainer.
- The exact shoulders the Stormwind Guard wear are not available to players - these shoulders are the closest you can get.
- Some guard members like Officer Jaxon patrol without a helmet.
- For a weapon any normal-looking one-handed sword will do. Just pick one that suits your tastes and fits the guard well. The guard does not use weapon enchants, it's up to you if you have an enchant or not.
- The guard do not wear capes, so you can turn yours off in display settings. Make sure you turn your helm on, if you want it to be seen.
The harder parts
- Gloves: There is no exact match for the gloves in the game. Closest is the
[Field Plate Gauntlets], a random but fairly common drop. The stats (which are random) don't really matter. They will probably pop up in the auction house if you keep an eye out.
- Shield: The matching shield is
[Maximillian's Shield], one of three choices at the end of the short Maximillian of Northshire questline in Un'Goro Crater. If you have done that quest already and chose a different option or have since sold/destroyed the shield you can instead pick up:
- DROP:
[Commander's Crest], dropped by Commander Springvale in NON-heroic Shadowfang Keep. It has the proper emblem, but is rectangular. - DROP or AH:
[Aegis of Stormwind], a random drop from mobs in the 55-60, it is the correct shape and emblem, but with blue trim. - QUEST REWARD:
[Shield of Darkshire], looks the same as the Aegis of Stormwind above, and is a quest reward from the Darkshire quest 
[10-30] Cry For The Moon.
- DROP:
Being "on patrol"
- Take a walk: Remember that the guards don't run, they walk. You can do this by pressing the NUM PAD "/" button to toggle walking on and off.
- You may want to pick an appropriate title to use, like the ranks given from battlegrounds, like
[Private] and on up. For instance "
[Champion of the Frozen Wastes]" isn't really fitting for a town guard in a dull patrol job, but it's still up to you. You could also always turn it off just leaving your name, too. - You can't hide your guild name from other players.
Enjoy your stint in Stormwind's finest!