I second the advice to familiarize yourself with the literature, and would like to add a strong word of caution at the same time.
A disclaimer: I speak out of personal experience with this topic, and I did not read most of the comments that you've already received (sorry, wish I had the time).
So here's my word of caution:
You must be aware that you are intentionally brainwashing yourself into a biased worldview by reading all of these books on suicide prevention.
Every book on suicide prevention has the premise that suicide is "bad", after all, that is why the author wrote it, and that is what they are trying to prevent.
It does not matter a lick how scientific their "data points are", if the premise that they are starting out with is based on a biased point of view.
You will join their ranks if you don't keep this in mind.
Therefore, in addition to all of the literature on suicide prevention that you read, I strongly recommend reading literature that supports suicide.
Books that support suicide use a different word, but it is the same thing. These books employ the same linguistic trick that books attempting to prevent suicide use: they use words.
Words have unspoken meaning associated with them, that only exists ephemerally in the culture in which they are used. You may or may not find this hidden meaning in dictionaries.
These two words have in fact the exact same meaning, when it comes to the end act. Their meaning only slightly diverges when you take the cultural connotation and circumstances surrounding their use. Nevertheless, they really should be treated (by you) as synonyms, because the reasons that the people you are trying to prevent from killing themselves are usually the same in each case.
Word #1: Suicide
- the action of killing oneself intentionally:
- a course of action that is disastrously damaging to oneself
or one's own interests
Word #2: Euthanasia
- the painless killing of a patient suffering from an incurable
and painful disease or in an irreversible coma. The practice
is illegal in most countries.
For your project, I will throw a devil's advocate accusation at you, and call you, and anyone in this thread who supports your cause, a terrorist and/or sadist. I will accuse you of in fact not helping people, but misguidedly (due to complete and utter ignorance on your part) torturing people by encouraging them to experience more suffering.
Further, I will claim that unless you can see this point of view, your project will be an utter failure, and will not achieve any success beyond what existing measures have achieved.
To understand suicide, you have to understand wanting to kill yourself, and you cannot understand this intellectually, you have to have experienced it yourself (or have a great "emotional imagination", aka ability to empathize). How can you help anyone with a concept that you have no understanding of yourself? That is the road to failure.
Suicide is a very rational reaction to life. I've seen people call those who want to kill themselves "selfish", when it's clear that it is the other person who is selfish, and wants the person to stick around and suffer, only to spare themselves suffering.
So, to start you off, you may want to compliment your reading by familiarizing yourself with real suicide notes, before you even think about writing a single line of code. Here are some I found via some googling (I cannot vouch for their authenticity though):
http://theholydark.wordpress.com/2012/08/28/some-painfully-e...
(references this page that is no longer online: https://web.archive.org/web/20130112214925/http://www.well.c... )