Choosing Poems for a Collection?

There is no science to it. I'd suggest not 'sticking to a theme' but rather adopting an inter-poem narrative of some kind, however vague. Just make the poems react and relate to one another. And it goes without saying that they should all be good! Beware propping up weaker poems using its surrounding counterparts as thematic ballast. It is a bit of a nightmare. I recently put together a chapbook-length collection for a competition and was substituting poems, tweaking order etc right up to the last day. But then it can also be a lot of fun. Good luck with it! -- My blog: One Last Wild / Enjambement