I have "Bargello Quilts" by Marge Edie. Has several nice patterns from easy to difficult.
Would also like to suggest taking the online course at Quiltuniversity.com - take the "Bargello Seasons" which is the beginning class. The class is only slightly more than the cost of the book. In the class you will make 4 different bargello and have an instructor (Ruth Blanchett).
My avatar is from Ruth's second class "Bargello Blues" where she teaches bargello in split patterns (ie you don't use the same strip all the time, nor do you "tube" the strip"), and the second part of the class you design your own and she assists.