I joined the local writers' group and went along to the meetings with something like dread. I'm very glad I did, because there were other people struggling with the same sort of problems. We all sat in a circle, listening to everyone else in turn. Sometimes there were 25 people there, which is an audience of Wembley proportions in the world of poetry readings. Some of the comments I got back were sharp, horribly on the nail. Not discouraging, just straight, and there were times when these responses would make me go away and re-think what I'd been writing. Then I started sending poems into competitions as I believe you're meant to as a way of testing them anonymously in a sort of critical market. It was when I won a couple of these that I thought I would carry on. I think "gave myself permission" is the phrase.
W.H. Auden, whom I've always admired, said a poem is never finished, only abandoned. I haven't a clue how they start up, or how they get finished, except that, like so much else, if you really put all your concentration and resources into it, then it starts to declare its nature to you and to offer you resolutions you would never have imagined, as you go along.