Heres a video explanation covering how to create circular lines, as well as using data views to create a profitable linear line. Also my thoughts and theories on what makes a better line. Hope you enjoy! 
[video=youtube;3AVWzGsQLks]http://www.youtube.com/watch?v=3AVWzGsQLks&feature=youtu.be[/video]
[video=youtube;3AVWzGsQLks]http://www.youtube.com/watch?v=3AVWzGsQLks&feature=youtu.be[/video]