Every poem, especially love poems, are unique and should be treated so. Creating unique examples from one's own feelings and experiences is the best way to create a memorable and meaningful line of poetry.
Many writing resources suggest writing love poetry from the heart by using one's own reactions and feelings towards the subject of the poem. Don't ignore the other feelings that go along with love, such as loneliness, fear, desperation and more. The author should allow his personality to come through the poetry. Don't be afraid of being too sappy or romantic, be authentic.
Other writing sources suggest to recall memories and specific feelings of the subject of the poem. Avoiding clichés by using specific examples also empowers a poem. The most highly regarded poets use memory and imagination to create pictures in the reader's mind; this is called imagery.