Look up drop hanging tables.
Make SURE the rope can support you.
Make SURE the knots can support you.
Make SURE what the rope is attached to will support you! <- By far the most important point, and the main cause for failure.
Make sure that no one will walk in and try to "save you." Having someone save you after you've already given yourself brain damage and now an expensive 5150 ticket to the psych ward on your dime while they pump you full of psychotropics to destroy your mind and place a giant red flag on your record forcing the rest of your life to be guaranteed shit is not what you want.
Getting wasted on alcohol is usually the method of courage discussed. Not much better than that has been discussed, unfortunately.
I never understood the last note thing. The family of people who have committed suicide never take it seriously anyways. An actual last will would probably be better, it gives the court system/police who find your body less work to do.