Step 1: Don’t write a love poem
Love is one of the most common themes of poetry, which makes it one of the most difficult to write about. Nearly everything to be said and written about love has already been said and written, many times over. The greatest masters of lyric and poetry have tackled this theme again and again. But don’t be discouraged. You can still write a good, unique, original love poem. But first you must push the generic idea of the "love poem" out of your head. Forget it entirely. Focus on what it is specifically about love that you want to write. Write about a person, an experience, any knowledge you have gained from your own life, and how this relates to love. Writing directly about capital-L Love is too vague, too general for all but the most skilled of poets. If you come at it from another angle, you’ll find it much easier to capture.
Step 2: Avoid clichés
This cannot be stressed enough. Unless you are dancing the razor-fine line of a satire, clichés should not appear in your poem. Keeping them out is more difficult than you might think. Clichés are what they are because of common usage, therefore they tend to be the first things to jump into our minds when searching for a description. Because we hear them so often, they’re easy to accept because they "sound right." But don’t confuse "right" with "familiar." When editing your poem, go through the lines carefully and make note of anything that seems like you may have heard it used somewhere else before. A good way to check is to copy the suspected cliché and paste it, in quotes, into Google or another search engine. (ex: "as red as a rose" or "eyes like fire") See how many matches appear. If the number is really big, consider re-writing that line.
Step 3: Make it Unique
One of the keys to a successful poem is making it unique. You want your poem to stand out from the others. You want your reader to slow down and consider your poem, not roll their eyes and say, "Oh brother, not another one!" This is also why step one is to avoid focusing on a general theme. Ask yourself, how is this love poem different from the thousands of others out in the world? Draw on personal experience, the individuality of situations, time and place. Sure, millions of others have fallen in love, but how many have done so with a girl in a red jacket at the corner of the playground in rural Wisconsin? Hearts have broken the world over, but how many of them have realized it in the center of that crowded café on 21st and Main, or assuaged their pain standing at that special bench looking over the river at dusk? Everyone shares similar experiences, yet everyone is unique. Make your poem as individual as you are.
Step 4: Use Imagery
One poem is like any other in that it still requires certain poetic elements to make it really shine. Use the senses to describe the look, feel, sound, smell and taste of love. Love connects to all varieties of emotion. With strong, vivid imagery, you can bring any of those emotions to life for the reader.