Check out the book that Michael Horowitz has created at Django Books. This book is turning out to be very necessary for me in my process of becoming a gypsy guitar player.
It was not easy, at first, to figure out how to apply all of the exercises in Michaels book, but after I was shown how each exercise can not only be applied to the open string picking patterns that are shown, but those same patterns can also be applied to other licks higher up on the fingerboard, and when I realized this I felt enlightened and very glad that I bought it.
Sometimes the book exercises can be slightly boring, but when I mix it up by using those picking patterns to try to invent other licks, then its much more interesting to me.