According to the Occupational Safety and Health Administration, "More people are killed while felling trees than during any other logging activity." Safety must be of utmost concern when approaching a tree to cut.
Protective clothing should be purchased along with your saw. Cutting trees with a chainsaw is particularly hard on the eyes and ears. Always use protective glasses and ear plugs. Steel capped boots and non-slip gloves are also recommended.
The American OSHA Regulation 1910.266 requires that employed chainsaw operators wear:
These requirements are for professionals who know what they are doing. A casual user should take note of this and have as much protection as a professional, if not more. Understanding that safety is important, let's fell a tree...