As a musician I learned to break things down into their component parts. As a writer I never had the same instinct. That's probably for the best since, as a musician, I often became so enthralled by the shape of the gears and sprockets that I never put them back together. Still, being able to practice a skill is a skill in itself. That's part of the reason I chose to read about poetry. Poets (generally) always seem concerned about the mechanics of language more than prose writers (generally). In A Poetry Handbook Mary Oliver suggests something like practicing rudiments or scales. The rudiments and scales of writing being, among other things:
Meter, syllable structure, feet, length
Sound, consonant varieties, vowels, alliteration, consonance, assonance
Imagery, metaphor, simile, personification, description, action
So I suppose the difficulty lies in balance.