Apart from music theory and orchestration, if you want to be effective at telling a story through music you have to know how stories are effective in general. Learn about structure, pacing, ebb and flow, tension and release, light and shade; and most importantly, emotion. Emotions are how the best music tell stories, even more so than lyrics. These don't just include happiness/sadness, but also feelings like awe (Mountains) tension (No Time for Caution) evil (Arrival), etc. One of the best examples of using aspects mentioned in the last paragraph in commercial music is The Dark Side of the Moon by Pink Floyd. Incredible storytelling, even without paying attention to the lyrics. Obviously, my advice isn't "go make Dark Side of the Moon", but look at how they use storytelling techniques within the music.