A suicide bomber is a type of inexpensive precision guided weapon. Unlike remote operated electronic devices or computer guided missiles, suicide bombers work on the paradigm that if you want something done right, you do it yourself.
Suicide bombers always involve at least two crucial components - explosives, and a human volunteer to transport the payload......although the term "volunteer" isn't applicable after the obedience serum wears off. The volunteer typically delivers the payload to the target by either concealing the explosives on their bodies, or driving vehicles filled with it (see also: kamikaze). Most suicide bombers chose to manually detonate to insure maximum effectiveness, although it's not uncommon for others to use timers.
Ways to prevent suicide bombers from chickening out
Just like cheap bottle rockets, suicide bombers can sometimes fail to detonate as planned. This is because of the unpredictability of the human psyche, and the highly illogical tendency for humans to want to preserve their own lives. Sometimes, it's also because of incompetence.
Needless to say, many people need a strong reason to want to click the red button. Assuming the person isn't all mad at the world or emo, then there isn't a whole lot that will convince any sane intelligent person to blow themselves up. To compensate, many of the organizations who deploy suicide bombers use motivational seminars (aka brainwashing) or appeal to their nationalist/religious sensibilities.