In order to select a target you also must know what makes a human easier or harder to tempt. There are an immense number of variables that go into the coversion difficulty equation, but the most important are the subject's age, intelligence, social class, devoutness, and acquaintances.
Generally the older the subject is, the more attached the subject becomes to the current life. Naturally, this makes them much easier subjects. However they do have some immunities such as declining opportunity for sexual temptation(however this may change as invent more sexual-aid drugs).
Intelligence almost always makes a subject more difficult to tempt. If you are looking for your first subject, make sure they are stupid. While stupid subjects are easy to tempt, the souls are not very satisfying.
Social class is a major indicator as to how attached a human will be to their life. The higher classes are usually much less accepting of death than the lower classes, because their lives are of better quality. On the same note, liberals are usually much harder to tempt than conservatives, because liberals generally look forward to the next life, rather than treasure the current life.
Obviously, the more devout a person is, the harder the person will be to tempt. However, do not label any person that participates actively in church as devout. Many of the easiest subjects are people of false faith.
The last factor in difficulty of temptation is acquaintances. Even if your subject is old, stupid, rich, conservative, and atheist, the subject may prove to be difficult to tempt if the subject has especially intelligent or devout friends. The people around your subject will always affect your temptations.
When reading this section, keep in mind that the article makes many generalizations. Not all conservatives will be easier to tempt then all liberals. Each target will be unique. Some will be immune to some attacks, but extremely vulnerable to others. With a little experience you will be able to recognize the difficulty of tempting a subject.