advice on revising past performance

i played the lead in my friend's first film. of course they were encouraging on set. but i am personally not proud of my performance. i was truthfully so preoccupied with self doubt (this was my first leading role) that i didnt do the prep i know i should have to give a good performance. its in post production now. any tips on revision so i can feel proud inviting people to the premiere? i am in the shame and fraud feeling currently.