balancing encounters for solo adventures

I have been building some solo adventures for 3.5 and encounter balance is proving difficult. The current technique i am using is to have an encounter of a cr suited to a full size party of the solo characters level but having only 1 encounter a day however this is obviously not ideal and will not work overly well when multiple creatures are involved.



How would you suggest i determine challenge ratings for a solo character?

balancing encounters for solo adventures