Read several issues of the magazines and journals where you plan to submit. The biggest mistake that a writer makes when submitting her work for publication is not being familiar with the type of work a specific magazine is looking to publish. You should always read an issue or two of each journal you submit to in order to get a feel for how your poetry would fit into the publication's overall style.
Read the magazine's submission guidelines carefully. You can find these guidelines in the front or back of an issue, or posted to the magazine's website. Many publications allow simultaneous submissions, meaning that you are free to submit the same poems to other journals, provided that you inform each publication once a specific poem has been accepted elsewhere. Some magazines, however, do not allow simultaneous submissions, and you will want to be aware of this when deciding which poems to send where. You should also follow the journal's instructions on how many poems to send and what information should be included in your cover letter.
Be sure to list your full contact details in the top-right corner of each poem that you want to submit. There are often multiple editors involved in publication decisions and one or several of your poems may be pulled from your submission to be passed on to another editor. It is important that your name, address, phone number, and email address are included with each poem.
Include a cover letter with your submission, even if the magazine's guidelines do not specifically request one. Your full contact information should be included at the top of your letter, including an email address for correspondence. Try to find the name of the journal's poetry editor and specifically address that editor at the start of your letter. The content of your letter should be brief, but should always include the titles of each poem you are submitting, along with a brief biographical statement about yourself. This statement can include any degrees you hold, a list of other journals where you have previously published, and your occupation. The format and tone of your letter should be formal; write your cover letter as you would a business letter.
Keep a detailed list of where you have submitted, the date of your submission, and the poems that you included. This is especially important for simultaneous submissions, as you may need to contact a magazine to withdraw a poem should it be accepted elsewhere.