There is an interesting series of articles on thermal rotation in the last couple of Soaring Australia magazines (www.soaring.com.au) -although I am not sure how you would access them in the USA. They state the difference in circling direction/vs speed/gust roughness/etc in great detail and has caused more than a little debate at recent club get togethers.
My theory is to crank it over hard, go against every gust or deflection and relax.
If your not going up in a Libelle, its not going to be the libelle thats the problem!

Bagmaker