I am african american and have relaxed hair how do I grow it long?

well i personally have been growing my hair out since forever and i did not get a relaxer til i was 16 so i still have long hair all the way down my hair and my aunt who is my beautician says the key is takin care of your hair its all about conditioning your hair like when you get done washing it put conditioner on and leave it for like 30 min , i personally use oil in my hair instead of grease