When we made our ghillie suit in the Army we used burlap jute. I feel this is the most effective material. The great thing about jute is that it is nothing more that burlap torn into the indivdual threads. Those of you that do not want to spend too much money (jute is expensive compared to burlap)simply purchase burlap and unravel it into the thin threads.
The links below show the what a ghillie suit made of jute looks like compared to cutting 2" wide strips of burlap. As I said I think jute is much more effective but it is MUCH more time consuming to construct.
http://www.army-surplus.com/ss_store/ghillie-suits.html
If you plan on using jute plan on it taking you days rather than a day of burlap.