The New Sudoku Players' Forum

[scsnesrud]

I'm aware of the advanced techniques but wonder which one to use next when unique rectangles and X-wings are done

[Leren]

There is no definitive answer to your question. The best thing to do is to have a look at some good teaching sites that have a lot of well described and illustrated solving techniques here and here.

Also, an article on the relative instance of solving techniques can be found here.

Leren