Hi, here are some references:

1. "Plane Algebraic Curves" by Brieskorn and Knorrer, around page 370.

2. "Plane Algebraic Curves" by Fischer, Appendix 4. 

3. The link 

http://mathdl.maa.org/images/upload_library/22/Polya/07468342.di020774.02p0260v.pdf

is a Monthly article about the Newton polygon as developed by Newton.

I especially recommend the first reference because it has a wealth of pictures.  
(However, it is a monster of a book.)