Overdosing or "ODing" as it is colloquially referred to as is another popular approach to end. Many have found it "peaceful" and painless. Though you can overdose on pretty much any drug, some are more lethal than others. Mixing alcohol in the picture won't be pretty either. Of course illegal drugs would have more serious effects, but I'm not going to discuss those.
Over the counter amphetamines could possibly kill you, but it is not likely. Others in the like will also cause various symptoms, not always death however. Many manage to just OD on sleeping pills and end up regretting it because it not only didn't kill them but it caused them even more pain. Some just cause painful vomiting.
This is not a smart approach to suicide. Though they did say Pentobarbital had a 100% fatality rate. It is difficult for an everyday person to acquire. Thus, this is not a very suitable way.
Effectiveness: 4
Note that this is for fun and not to be taken seriously.