Pronominal verbs are verbs that need a reflexive pronoun in addition to a subject pronoun, because the subject(s) performing the action of the verb are the same as the object(s) being acted upon.
French has three types of pronominal verbs: (1) reflexive verbs, (2) reciprocal verbs, (3) idiomatic pronominal verbs.
There are two steps in conjugating pronominal verbs. First, take the reflexive pronoun se, change it to agree with the subject of the verb, and place it directly in front of the verb. Then, as with all verbs, conjugate the infinitive according to whether it's an -er, -ir, -re, or irregular verb.
The most common pronominal verbs are reflexive verbs, which indicate that the subject of the verb is performing the action upon himself, herself, or itself. Reflexive verbs mainly have to do with parts of the body,* clothing, personal circumstance, or location.
Note that many reflexive verbs also have a non-reflexive use; that is, they can describe someone performing the action of the verb on someone or something else: Elle se promène. She's taking a walk. vs Elle promène le chien. She's taking the dog for a walk. OR Je me lave les mains. I'm washing my hands. vs Je lave le bébé. I'm washing the baby.