Hi there :)
I’ve just had my debut pamphlet out from a great small-press called Red Squirrel; basically I’d had things in various print magazines and decided to put together a few poems (not an actual pamphlet at this stage) and send them around a few small-presses; Red Squirrel said yes and then the journey began, which ended last October, with the publication of Every Salt Advance
So basically, my advice would be to just send around some poems to small presses, with a coversheet as well explaining where you’ve been published before and what you’re about. Perhaps email the individual publishers before to see if it is worth your while sending things; you need to make nice to them as much as possible.
Hope this helps, let me know if you have any other Questions, would be happy to help :)
xx