In the independent form: sé (się), before the verb: si. In conjunction with the infinitive, participles, and gerund, the reflexive pronoun is placed after the verb and is spelled together: lavarsi, lavandosi.

Reflexive pronoun occurs only in 3rd person:

mi sento - I feel

ti senti - you feel

si sente - he / she / it feels

si sentono - they feel