How can I remember when to use 'être' in the perfect tense?

Etre is the auxiliary that is usually used with verbs that mean 'coming' or 'going' in French, as opposed to avoir. You can use the 'DR MRS VANDERTRAMP' acronym to help you remember: Devenir (to become) past participle: devenu Revenir (to come back) past participle: revenuMonter (to climb) past participle: monté Rester (to stay) past participle: resté Sortir (to leave) past participle: sorti Passer (to pass) past participle: passéVenir (to come) past participle: venu Aller (to go) past participle: allé Naître (to be born) past participle: né Descendre (to descend) past participle: descendu Entrer (to enter) past participle: entré Rentrer (to re-enter) past participle: rentré Tomber (to fall) past participle: tombé Retourner (to turn around) past participle: retourné Arriver (to arrive / to come) past participle: arrivé Mourir (to die) past participle: mort Partir (to leave) past participle: parti