There are some fundamentals essential to achieving a good cast. I have listed these below, however getting them right takes plenty of practice and I would strongly recommend having a lesson or two. This will prevent you adopting bad habits, or identify faults you may already have.
So less line outside of the rod tip means less power, a shorter stroke length, narrow arc and a short pause at the end of the acceleration stroke. As the aerialised line gets longer so these variables will increase as the weight of the line will bend the rod more..