"Common Problems in Orchestration" by Professor Alan Belkin is designed to follow up and add to the Garritan/Rimsky-Korsakov online orchestration course. It will add to the concepts and skills in orchestration you have already learned from Rimsky-Korsakov’s book. Each mini-course has a specific problem in orchestration. The examples following propose various solutions, beginning with poor ones (typical of beginners) and finishing with a professional version.
"Stucture Your Music" by Professor Terry Dwyer deals with form and discusses good development to make sure your music is well structured.
The Interactive Principles of Orchestration has recommenced. This is a complete orchestration course based on the classic text with online guidance and interactive flash scores.