Some comments to further expand on t's general points:
Details can be found at http://saints.catholic.org/index.shtml (currently features a banner ad for the U. S. Army--Be all the Martyr YOU can be!). They have a FAQ.
But generally saints were initially just sort of spontaneously adopted by members of the Church, then the Vatican got into the act because of fraud and lack of control in the 10th C. Popa JPII formalized the process to 3 steps: Veneration (holy), Beatification (blessed), Canonization (saint). This has been controversial in that it is really easy for people to get venerated and beatified. This has led to a lot shady and political figures getting the aura of "saintliness" without getting canonized.
That is not to say a lot of embarassing characters don't still get through. It takes time, organization, and luck (note that none of these things have anything to do with saintliness--it is about public relations really). My favorite recent example was an Italian woman canonized about 5 years ago (I don't remember her name but at the time I sent emails to all my catholic friends). Anyway she lived in this century and she was canonized because of HER FAITH IN HER HUSBAND! Apparently this guy was a terrible husband in all the usual sordid ways (including physical abuse!) but she never left him and continued to pray for his sorry ass. Well, her husband got the spirit later in life and this was considered her "miracle" necessary to get her canonized.
Also, if you read about alot of the saints who aren't church or government leaders, you mostly think they are pretty amazing people but likely would be "cured" by happy pills and psychotherapy today. Look at all the "stylite" saints (guys who lived on top of pillars).
Raised catholic and living with it one day at a time.
Blessed are the rich for they will have freedom of choice. Blessed are those with a liberal conscience for privelege will not be challenged.
*The New Beatitudes"