If you are talking about people in a country that is trying to democratize (as opposed to individuals in foreign countries trying to help some other country democratize), the most effective way to encourage democratization is to organize one's acquantances. A person can form a group (even an informal one) and that group can push for more rights.
The group can do things like constantly petitioning the government to reform. For example, if government officers refuse to follow the rules, the people can petition to the officials' bosses to make them obey those rules. This would help to establish the idea of the rule of law which is important for a democracy. People could also demand that rights like freedom of speech be honored.
Of course, this can be dangerous if the government that they are trying to change is currently authoritarian. Individuals in such a society who push for their rights may end up in trouble with the authorities.