This is a very broad question, really too broad for an enotes answer. Yeats wrote hundreds of poems in the course of a very long working life and his methods and techniques varied not just as he developed as a poet but also in relation to the subjects he wrote about. If you take a poem like 'An Irish Airman Foresees his Death', you will find very simple language, regular rhyme and rhythm, a simple four-stanza structure and a calm, balanced tone, all of it carrying a theme of some complexity. On the other hand, 'Easter 1916' is much more animated in its opening, becoming more reflective and philosophical as it progresses. 'Sailing to Byzantium' is on another level again philosophically speaking. 'Among Schoolchildren' shows a different Yeats altogether.

If you could narrow your focus to particular poems or even different periods of Yeats' writing life your question would be easier to answer.