I think a good introduction to his prose is Post Office, it's an easy read. If you like that, then you can move on to his other novels like Ham On Rye, which feels more real and dark, especially when he talks about his childhood.

My favorite poetry collection is "Burning in water, drowning in flame", but most of the poems are thematically and stylistically aligned.

He also wrote a ton of short stories, mostly dark and crass. They are all quite short, so literally take your pick with those.

I like the novels above the other stuff personally.