Altars to San Simón always have a doll or effigy of some kind representing him along with cloth that is characteristic of the indigenous peoples of South and Central America. People turn to him with requests of good health, family harmony, job security, good crops, and the like. He has what is referred to as a dark side as well, but I like to refer to it as human. He is said to grant requests that have something to do with revenge and success at the expense of others.
Learn how to make a San Simon doll here!
The Art of Conjure: San Simón Wishing Spell