The best thing you can do other than writing is reading. Find lyrics yo love and really get into them. Find interviews with the song writer or things they have written other than lyrics. Immerse yourself in good music and lyrics and poetry.
The major difference between beginners and experienced songwriters (or anything really) is usually complexity of thought and how naturally they can apply that to their writing. As you write more and are honest with yourself about what your writing you'll learn how to think that way. Learning about great song writers and how/what they wrote is a great way to get clues on how you might progress and get better but it is all about actually doing it and not really about what you know.
All the rules and advice and guidelines in the world won't make you a good writer.
