Research Spiked Barricades
Only the Orcs have the option to upgrade their buildings so they damage melee units that attack them. Take full advantage of this by researching the Spiked Barricades at the War Mill. This can help you defend buildings that are attacked and can bring the enemy unit's health down and sometimes kill off several units before the enemy figures it out. If the enemy is using a lot of ranged units do not bother researching these upgrades. However, if they are focused entirely on melee units and are attacking buildings, research it.

Watch Towers vs Orc Burrows
Orc Burrows alone aren't always the best for defense. Typically new players build a lot of Orc Burrows and no Watch Towers because they do not understand their strengths and weaknesses. Orc Burrows are primarily used for defeating early attacks and for adding defense to other defensive troops and Watch Towers. Orc Burrows have 5 armor compared to Watch Towers (which have 3 armor). Burrows also have heavy armor instead of building (fortified) armor which makes them very weak. Orc Burrows also need to be manned by Peons while Watch Towers do not. Typically players build way more Orc Burrows than they have Peons to man them. Instead combine Orc Burrows with about 2 Watch Towers. Build buildings around the Watch Towers or place them next to trees to make them more difficult to reach.

Defending Expansions
Typically most players have no defenses for their expansion and simply Teleport there or walk. You can also build one Orc Burrow and several Watch Towers to defend an expansion. If you have more than 5 Peons at your expansion build additional Orc Burrows.

Use Orc Burrows to Supplement Town Defenses
Fill each Orc Burrow with 4 Peons. Leave the Orc Burrows empty until they are needed, then grab the Peons on Gold or Lumber to enter the Burrows when they are attacked. Use Peons to repair the Orc Burrows while they are being attacked. Remember to hit R or click on the repair button rather than trying to right click on the Burrow which will instruct the Peon to enter the Burrow if there is room. Build additional Peons to help repair or man the Orc Burrows. Adding units increases the fire rate of the Orc Burrows as the units inside throw more spears.

Build Orc Burrows for defense around the Peons mining Gold. You can place lines of Orc Burrows on either side of the Peon line. If they are attacked, place 4 Peons inside and surround them with Peons using repair. Play the pop in pop out game. Have a Peon on the outside repairing the Orc Burrow while it is being attacked. If the enemy focuses on the Peon, have it get inside the Orc Burrow. When the enemy focuses again back on the Orc Burrow, pop a Peon(s) out and repair again. Make sure you get Spiked Barricades and Reinforced Defense to make them stronger.

Orc Burrows have a normal cooldown of 2 seconds and 0.8 seconds with 4 Peons inside.

Place the Burrows in such a way that their field of fire can cover your town. Also make sure to put them near the Peons on Gold and Lumber so that they don't have far to walk to get into the Burrows.

Battle Stations
Pressing the Battle Stations button on a specific Burrow only calls Peons to man that specific Burrow. If you want to fill all of your Burrows group select the Burrows (you can double click on one of them) and press the Battle Stations button. This will fill up all of the Burrows if there are enough Peons. You can do the same to return all of them back to work.

Town Building
Proper Town Building is very important for Orc players. Burrows need to be placed such that they are easy for the Peons to get to for repairing and for battle stations. The Burrows also need to be able to defend the Orc buildings.

[ Click to Enlarge - 147 KB ] This Orc Town is nicely built. The Peons can easily reach the Burrows.

Item Usage
Two Items Orc players should regularly use are the Speed Scroll and Healing Salves. Salves should be purchased to use on Grunts (or other valuable units) after battle. Later on you can use the Shadow Hunter's Healing ability combined with Salves. Allied units also might want to buy Salves for their own units at your store. Speed Scrolls should be purchased to use for escaping battles or during battles so that Grunts or allied units can more quickly reach their targets.

Spells and Abilities

Use Sentry Wards
Sentry Wards last 10 minutes! The Witch Doctor comes with this spell initially, so build one and place Sentry Wards around key locations such as Fountains, enemy towns, enemy mines, key traveling points on the map, and your town, in order to spot invisible units. If you're having trouble with Night Elves using Shadowmeld or Blademasters using Wind Walk, the Sentry Ward is the perfect solution.

Use Purge
Make sure you get Shamans with Purge to slow down enemy units and Heroes especially.

Get Bloodlust!
Build Shamans and research their adept and master training so that you can get Bloodlust. Turn it on and bring several Shamans along with your army.

Get Pillage!
Pillage is an excellent way to generate resources while attacking or eliminating enemy towns. Make sure you always research it when using Grunts or Raiders to attack enemy buildings.