A PDF can provide the text, but orchestration is ultimately an aural skill. Kennan famously emphasized that orchestration cannot be learned solely through reading; it must be heard.
Distinguishing between the "possible" range and the "effective" range. The Technique Of Orchestration Kent Kennan Pdf
Take a full orchestral score and try to reduce it to two staves for piano. Then, take Kennan’s advice and try to re-orchestrate it. A PDF can provide the text, but orchestration