The user was asking for painless ways.
Try to order or find in a flower shop the plant monkshood. It contains one of the most lethal alkaloid on the planet, that being Aconitine. Mix the strongest alcohol you can get, such as grain alcohol. Then crush up the roots of the flower, and mix that in the grain alcohol. stir and mix for a while, maybe 2 hours, and then drink it. You'll be dead painlessly within an hour.
DISCLAIMER I do not encourage suicide. I believe that you ought to live and enjoy your happy life. I am not suggesting or responsible for your death. This is purely educational.
http://en.wikipedia.org/wiki/Euthanasia_device Good place to start, sorry i wasn't very technical. In saying simple 3 stage i meant that there are three drugs involved in three separate cylinders.