Trees that hang over your house are more difficult to trim because one slip could cause a lot of damage. Care must be taken to keep control of overhanging limbs being cut to avoid damage not only to your person, but to your property. The proper equipment is a necessity. Cutting corners for can result in damaged roofs or broken windows. For very large trees, call in a professional tree trimmer that can bring in lifts and some seriously heavy duty equipment to handle tough jobs. Smaller trees are easier to handle.
Set your ladder, making sure that the feet are on even ground, and tie it off to the tree, higher up to stabilize it and make sure it isn't going anywhere.
Put on safety equipment: boots, gloves, eye protection, ear protection, and hard hat, at the minimum.
Cut the branch with the chainsaw, moving from branch tip in toward the tree in sections.
Tie a rope off close in to the tree, lower than the branch that you are cutting, if you are doing the job alone. Tie the loose end to the section you are getting ready to cut. When you make the cut, the loosed section should swing back toward the tree in a controlled arc. You can then untie it and drop it to the ground in a safe area.
Repeat the process until the overhanging limbs are all cut back to a desirable length; enough to ensure the safety of your home through threatening weather conditions, while not making the tree look lopsided. Branches on the other sides of the tree may need to be cut in order to give the tree a balanced look, if overhanging branches must be cut too far back due to existing damage or hazards that they may pose.
Cut branches from sectioned limbs and haul off. The blocked sections can be disposed of as well, or stacked and cured for firewood.