Daily Film Scoring Bits was an almost daily blog (now it’s an archive) of orchestration tips from Robin Hoffmann, a composer for film scores and international artists. On a nearly daily basis he offered a new tip or piece of advice regarding the composition, orchestration and technical aspects of creating film scores or orchestra music in general. I’ve read them, all the way back to his first daily post in his 2010 archive.
Even if you have no interest in film scoring in particular, there are plenty of tips on orchestration in general.