Think of a topic that you feel would make for a great song and write it down. It is recommended to purchase a songwriting book called "Songwriting for Dummies."
Start to write down catchy words that have to do with the topic that you picked for your song. Make a list of them.
Once you have some ideas flowing, you need to think up a catchy "chorus." Let your imagination run wild.
Once you have found a catchy chorus, fill in the blanks. Start experimenting with some catchy words that you wrote down, and keep in mind that you can change them around to make it flow better.
Ask others for their opinion. When you are putting in long hours on any type of writing project it is easy to get writers block. You will be surprised how one opinion or suggested word can make your song go from good to great.