Saying goodbye is not something that most people would want to go through before committing suicide. However most anyone who is considering the idea is probably so far into their own emotions that they probably do not care. So, the easiest thing to do is gather everyone to whom someone wishes to say goodbye to and tell them with all due honesty about the situation. Telling each person individually is also an option, if one wishes to relive the moment again and again. Another option is to leave a suicide note. As for what goes in the note, one will not find that in this section but it is always an option. Lastly if someone just wishes to not go through the process, one can commit the act and leave the loved ones to handle it themselves. A good idea is to make the last time one was with them a happy and fun experience, because this is most likely the last image they will hold of. The "formalities" altogether might be skipped to commit suicide, plain and simple.
When noticing anyone considering suicide, assuming that murder–suicide might occur may help save multiple lives.