To easily unlock the achievements that require you to have an accuracy of 95% or above, set the difficulty to easy. When the mission begins, fire one shot at an enemy and make sure it is a hit. Then take out your dagger or sword and kill the remaining enemies with that weapon.
-When an ally is fighting hand-to-hand with the enemy, help him. Sometimes they will get killed and you could end up alone.
-When you finish securing an area, reload your weapon to have a fully loaded weapon in case you are spotted by an enemy.
-Reloading a weapon takes alot of time. It pays to plan your reloading time and engage in hand-to-hand combat when facing a greater enemy force. Keep mobile and be aware of your perimeter when engaging.
-High ground offers you a better vantage point and firing position.
-During a stealth mission, stay out of areas with lights and the enemy cannot see you. Note: If you fire a shot they will be able to spot you.
-While shooting an enemy,straif from side to side. This helps to avoid enemy bullets.
-If you cannot see an enemy due to trees, use your crosshairs. If it turns red, then you are aiming at an enemy. If it turns green, then you are aiming at an ally.
-You will find wagons, stone walls, and baskets on the battlefield. Use them as cover while you are reloading, getting suppressed, or low on health and looking for a medi-kit.
On the first level of the Confederate Army on the road, go right before the bridge to find a fence. Walk up the fence line tapping A and pick up the Gatling gun which has unlimited ammunition. Unless you save before you die you will have to do this cheat again.