You've finally selected the poems for your book and edited them carefully, and found the right publisher...congratulations! Your work isn't done, just yet.
You might still be undecided about the title of your book, if you already started out with one, make sure it reflects your final product after editing. It's a good idea to make sure that your title is unique, and not similar to several other books on the market. An author's worst nightmare is to type their book title in a search engine and find ten other books with the same title. Find something that makes your book stand out, and avoid using cliches. Your book title is the first thing people see, so take your time in choosing a title. Write several ideas on paper or type them in your computer, and say them out loud. What does your title sound like? Do you feel confident with the words? Does it sound like a book that you would buy? If the answer to all three questions isn't "YES"...then wait until you find the title that resonates with you and get a second opinion. It's that important.
If you have researched your chosen publisher's website, you'll find that they offer many services, including formatting. If you are an expert at this, you can do it yourself---meaning, you're a professional at word processing and know Word inside and out, with one hand tied behind your back and your computer under water in the Arctic. Maybe that's hyperbole, but what I'm saying is, one of the reasons self-published books don't get read is because of poor, sloppy formatting. Paying for professional services is costly, but can make the difference in a great-looking product, or one that is mediocre in appearance. Professional formatting offers custom styling options, including photographs, graphics, table of contents, and more. On some publishing sites, you can preview books done by other authors to see their finished product. Many times, you can tell the DIY jobs vs. the polished works. If you decide to format your own book, make sure to upload your copy exactly to their specifications, or it will be returned to you to be reformatted. Complaint pages are full of posts where authors have had their copy rejected several times because they didn't follow the upload guidelines. It's not that the publisher wants to make money (well, they do) but if you don't format properly, they can't print the book.
Once you have completed the formatting of your book, either on your own or through the publisher, you'll need an eye-catching cover. A publisher can create a book cover for you at a very high price tag, or, you can shop around for a graphic designer who can do the same work and have it camera-ready for a lot less. If you are part of a social-media community, ask poets and writers in your network for referrals. I found a wonderful professional graphic artist who did an excellent job in capturing the theme of my book for a great price. Look for someone who is a real graphic artist, not just someone who claims to be one. A real graphic artist should have several images of their work on display in different mediums, including flyers, CD covers, business cards, posters, and anything clients want done. Be open with them about what your work represents, and listen to their suggestions. Trust them to do the job they are trained to do. If something isn't working, let them know. A good graphic artist is an author's best friend! Know the terms of their contract before employing them, usually a deposit up front, and payment in full when the work is completed. Get a quote and have all of their money so you can pay them as soon as the work is completed. You expect your job to pay you on time, and as a professional, the graphic artist is owed the same respect. Be sure to give them credit on your copyright page!
As the saying goes, you only get one chance to make a first impression. Although this may be your first book, your goal is not for it to look like it's a first book. Many authors' books don't get a chance to be read because of poor planning or an unprofessional look. Put your best effort into investing in your work, and letting your light shine!