I have written a score for a piece of mine in Sibelius and am now doing a mockup of it using East West's Hollywood Orchestra. I want to add some choir at a climactic point in the piece. I haven't written for choir before so I was wondering are there any particular guidelines to follow, any dos and don'ts etc. Do you generally treat the harmony in the same way as when writing for instrumental sections or instruments or is there a different approach? Thanks.