When you write a song, you need to right about a subject that you know about. If you look at country music right now the reason they are so popular is because they write about stuff people relate too. They same goes for all music that was extremely popular people can relate too. Take the eighties for instance hair metal wrote a lot about sex and drugs, and what are the known for cocaine and crack whores. So dont try to write about doing drugs when you have never done them, and the same goes for everything. And thats why heartbreak songs are so popular, because its something everyone has experienced. So make sure when you write about something personal and dont follow typical song conventions for lyrics, you can write it as you hear it in your head and the same goes for the instrumental parts too.