I don't usually enter them. I question the notion of competition in art – though I can see that, to many, big prizes and high recognition seem well worthwhile. (And then, every submission to a magazine or anthology is a kind of competition.)
I do sometimes take part in smaller competitions with no remuneration, such as those offered by Robert Lee Brewer at Poetic Asides. He likes to acquaint his readers with different poetic forms, and often gives us a month-long challenge to write in a particular form. I enjoy trying out new forms – some more than others – and trying continually for a month is a great way to learn.
I like that it's called a challenge rather than a competition. Although a number of poets take part, it's a friendly experience. Essentially, we're all challenging ourselves.
I'm not so anti-competition that I'm not thrilled to have been placed in the top 10 a few times recently!
In the Haiku Sonnet Challenge I came 7th, with Walking Around Town.
In the Dizain Challenge I came second, with Burning.
In the Trimeric Challenge I came third with The Peaceful Place and also 10th with Reminders.