Aside from writing every day, which will make you a better writer, and reading good books and poetry which will do the same, try this:
At any given time of day, pause your mind for a moment and look around and think to yourself, "How could I describe this?" Practice in your mind describing things, people, settings or events. Use all your senses, go over the top.
Carry a notebook with you too in case you really compose something good.
Hope that helps.