i would say that u have to know the scales good enough that
when u sing/whisles a melody in that scale, u have to know how to play it at the same time.. this way, u can find melodies u can use.. and maybe spice it up with some shredlicks.. listen to Michael Angelo's No Boundaries..
a good ex. on spiced up melodies.. = )
and.. learn some short sweep-patterns.. and some short alternate-runs.. this helps alot..
i would recomend 3-notes per string scales for the alternatepicking..