This is a small forum with around 70 members but only about a dozen active members. It is run by two very knowledgable administrators-teachers that are very helpful with pointing out errors in orchestration and give useful suggestions for composition. I feel it’s a bit cliquey and over moderated but might be useful for someone interested in composing, Good luck, I didn’t fit in very well myself so I have become one of the inactive members.

This is a huge forum for classical guitarists all over the world, very friendly place where you can upload recordings and transcriptions and compositions and also download a vast library of music. This forum also has a fairly large community of Luthiers.