Never forget that the subject is as important as your feeling; the mud puddle itself is as important as your pleasure in looking at it or splashing through it. Never let the mud puddle get lost in the poetry-because, in many ways, the mud puddle is the poetry.
One good way to start writing poetry is to read all kinds of poetry: not just in order to imitate but to fill up your head with it, to absorb it, to make poetry an essential part of how you view the world.