The most important thing is to be safe. Of course, we recommend you contact a professional tree service. We have the training and the proper equipment to cut tree limbs safely and efficiently.
Use a ladder or extension ladder to reach the branches.
Make sure the ladder is stable and set it up against the tree in such a way that you will have a good grip on the tree limb when you cut it.
Wear gloves and safety goggles to protect your hands and eyes.
Use a saw with a sharp blade to make the cuts. A dull blade can cause the branch to split and may result in injury.
Cut the branch slowly and steadily