Now that you've written your chord progressions, melodies, counter-melodies, contrasting sections, introductions and outros it's time to start thinking about how to write IDIOMATICALLY for the instruments you've chosen. For the sake of this exercise I've chosen to do a deep dive into the three main sections of the orchestra; Strings, Woodwinds and Brass. 

You should have a go at writing for each one of these sections, and really get the feeling for the strengths and limitations of each instrument. Click on the links below to navigate to each one:  

Below are some general ideas on how to orchestrate and arrange for an entire orchestra.