Parenting struggle

When I first started having kids people would tell me all kinds of things but mostly I would heard, "Enjoy them while their young, they grow up so fast!" My oldest recently turned FOUR. It is really hard to imagine myself with a 4 year old and an 18 month old. More than that, it is hard to find that right disciple for my oldest daughter. The years between 3-4 has been very challenging for Grace and I. She is a very independent, high spirited, and know it all kind of person. I see Grace doing awesome things in her life with her strong willed, independent nature. But, in this nature that she has, it is very challenging for me to figure out what works with her. Recently, she has found this new found "big kid" attitude that apparently turning 4 has given her wisdom beyond her years and she thinks she is smarter than anyone else. She has spent MUCH time in time out, getting toys taken away, and losing TV time. I am looking for some mom's who know this challenge. Share your wisdom. Share what works for you.