The first thing to do when composing a song is to find a theme. Your song won’t be very successful if you don’t have an idea or topic that it is about. After you have the theme, you must decide what style the song will be. Do you want to it be a slow, acoustic style of soft rock, or a quick paced, upbeat hip-hop beat? Once you have the theme and style selected, the rest relies on musical ability. One of the most important things to remember when writing a song is to have repetition of sounds. If the song is constantly changing and doesn’t have a recurring beat then listeners will have a tough time listening to it. Almost every song has a chorus, a line or group of lines repeated throughout the song. Establishing a chorus will allow you to build off it and make the rest of the song musical. Another thing to include are verses. These are lines or groups of lines that aren’t the chorus. Between the two, chorus and verses, it makes up the majority of a song. There are a few other techniques and parts to a song. A bridge is something that links phrases together. They can be used in between verses or the chorus. Intros and Outros are other techniques commonly used. Some songs have very short introductions such as two measure of music whereas some build in for many bars.
Long story short, there are many things to consider when composing a song. Establishing a solid them and style is the most important. Once you have control over these, the rest should be history!