Perfective describes an event while imperfective describes either a process (progressive) or many events (iterative).

She will like me as soon as she will see me because I am so nice. - Perfective. Я ей понравлюсь...
She will like me during all the Saturday. - Imperfective progressive. Я ей буду нравиться...
She will like me each time I will be nice. - Imperfective iterative. Я ей буду нравиться...