Avoid cliche and forced rhymes. An easy beginning mistake in writing lyrics is to place the importance of the rhyme above anything else. Rhymes can be very effective when used cleverly, but they can just as easily make lyrics feel amateurish if you're building a song specifically around them. The same idea applies to overused cliches and cheesy sentimentality as well. Although you may feel you need to rely on bombastic emotional insights to get your feeling across, you'll get better mileage by toning it down for something more intimate.
