Trees aren't always where you want them to be, or have a disease and need to be removed. Cutting down a tree is a dangerous undertaking best done by professionals. If you are determined to cut down a tree on your own using a chain saw, take safety precautions to ensure no injuries occur. Chain saws can kick back and cut you even if you are careful, so it is best to do this project with a helper who can be there in case of an accident.
Move all objects out of the way. When the tree falls, there is always a chance that it won't fall in the direction you want.
Designate a safe area to go once the tree starts to fall. Set up a stake with an orange tag tied on it so that your will notice it, even in the moment when the tree is falling. Make sure the location is as far away from the tree as possible and to the side of where the tree is suppose to fall.
Decide which way you want the tree to fall. Pick a direction away from immovable objects. If the tree is leaning a certain way, it is best to have it drop in that direction if possible because it might fall that way anyway.
Saw a notch in the base of the tree on the side where it is supposed to drop. Cut straight into the wood at the base. Make a second cut at an angle, a foot above the first cut. Have the second cut come down toward the first and meet to form a point. This will create a notch cut. Knock the loose wood out of the tree. The notch can also be reversed so that the straight-in cut is on top and the angle cut is below and comes up. Make sure the two cuts come to a point and that neither overcuts the other. The cuts should not go farther than a third into the tree and not less than a quarter.
Make a separate cut on the other side of the tree, just above the point formed by the notch cut. Saw straight into the tree horizontal to the ground. The tree will start to fall at some point as saw into it. Have the other person stay in the safe zone and warn you if it isn't falling the way it is supposed to so you will have a chance to get out of the way.