Think about an idea, personal experience or emotion you've had that would be relatable to most people around the world. Write down that idea and place it in a safe place so you can refer to it later. It doesn't have to be in poetic form now.
Practice writing thoughts about things that don't pertain to you personally, but would to other people. As a song lyricist, you should also tap into universal truths about feelings, emotions and perceptions of the world others would think or talk about. Write these down and save for later.
Scan newspapers, magazines or listen to people converse in public places to get ideas that could be incorporated into a song. Not all songs have to be about love, even though infinite songwriting ideas still exist in that category. Songs about world events, without being too immediately topical, work well in a number of musical genres---particularly Country.
Take your idea sheets out and start brainstorming images in your mind behind the idea. Think of words that paint a picture to readers. Describe that idea or emotion in verse form rather than just tell about it.
Construct the structure of your song lyrics and know where certain sentences will be placed throughout the song for maximum emotion. Work on your chorus first that opens your song before getting to the main verse. Place the crux of your idea into the chorus using a rhyme scheme that doesn't use too many syllables to alleviate excessive rhyming. Write an opening line that attracts curiosity.
Design your verse the same way you did for the chorus, though expanding on your idea a little further. Sometimes this means opening the flood gates to emotion. Have the idea link to the lyrics in the chorus to keep your idea cohesive.
Use various rhyming schemes that go beyond the simple ABAB format that rhymes each line of verse. Try an ABAC scheme where you rhyme the first and third verses in four-line stanzas. Or use an ABCB rhyme scheme that rhymes the second and fourth verse.
Expand the idea you conveyed in the chorus and reveal something different to that idea during the bridge or mid-section of your song. A bridge or mid-section usually is in a different key for variety and should reflect a different perspective in the lyrics. That perspective could be a counter emotion to what was said before, though providing logic that can lead back to repeating the chorus and rounding out the idea by song's end.
Change the line length and meter of each section throughout your song to create variety. For instance, make the chorus using short lines, use longer lines for the verse and create different meter construction for the bridge. Be sure to write words that fit into a repeat of the verse since verses are usually repeated at least once in song structure.
Construct lyrics using action verbs instead of passive ones. When you do, it keeps the song moving so listeners can feel the emotion. Also use plenty of descriptive adjectives to describe thoughts and feelings.
Write music with your lyrics to see how they fit together. If you're working with a composer, have him send you the melody of the song first so you can get a better idea of how the song will sound before you write lyrics. In other cases, writing your lyrics first may inspire the composer.
Sing the lyrics if you have a melody written to go with them. If you don't sing, have a musician friend sing the song for you to hear. This is the best test method to see how a song works for a singer.
Hone your lyrics and change certain words to make it easier for a singer to sing. Take suggestions from your singer friend for word changes. Have other singers sing the song to see how certain words roll off the tongue.