Identify recently published poetry books that you admire or contain work similar to your own. Find out which agents represented the poets. Many books include the name of the literary agent on the acknowledgments page. If not, contact the publisher and ask for the details.
Make a list of the literary agents that you wish to approach. To increase your chances of finding an agent, consider contacting them all.
Write to each literary agent and ask whether he would consider taking you on as a client. Don't send a template letter, write individual letters to each agent. Keep the letter brief and make sure it's well written. Include a brief description of your poetry but don't send samples of your work at this stage. Interested literary agents will ask to see examples of your work.
Research the agency's submission guidelines before sending in examples of your work. You will usually find this on the agency's website. If not, request the guidelines from the agency.
Check contract details carefully before signing the contract. Be clear about the contractual obligation between agent and author. Ensure you know what percentage of your earnings the agent will take as commission and any additional charges that you might have to pay.