I think it is better to buy a software program for load flow study. Such program will contain various methods like Newton=Raphson or Gauss-Siedel or some other methods, which give lot of guidance for making a load flow study. One of the best programs is PTI's, though it is very expensive. From search engine you can have access to lot of programs.
. The dissertation gives a chapter on the new load flow solution techniques that are neither Gauss Siedel nor Newton Raphson. I use it to do 35,000 bus load flow and ATC studies on the eastern grid.