composing in general, any exercises that get your mind working and thinking
of new musical ideas can be helpful. This
might include finding themes by looking at your environment, going to jam
sessions, composing by looking at a piece of art or reading poetry, etc. More technical exercises might include composing
at versus away from the piano, using contrapuntal variation, and improvising
to find musical ideas. Take a look at
the composition section for many more possible composition exercises.
arranging and orchestration, exercises focusing more on theory are more
helpful. Good exercises include
playing through the Bach chorales, scoring pieces for various ensembles, and
becoming familiar with the main instrument groups and their characteristics,
as presented in Alfred Bladder’s Instrumentation/Orchestration. You may want to read through the articles
in the theory and student prep sections for more ideas. Also, working with a composition instructor
can ultimately help to understand the nuances of orchestration and select
exercises geared towards your needs in composing.