You can interpret a song by analyzing it in its specific context, consulting a dictionary and thesaurus, consulting the opinion of those around you and giving yourself enough time to complete the interpretation. You may also compare your interpretation to existing ones on websites such as SongMeanings.
The first step to interpreting a song is determining its specific context. The most direct way to do this is to research other people's interpretation of the song and to see if the lyricist offered thoughts on the meaning of the song in any articles or interviews. You may only find information on certain parts of the song, but this can help you analyze the rest of the song based on the information you have.
While you determine most words and phrases through intuition, use a dictionary and thesaurus to make sure you understand the meaning of specific words. This can also help you determine when a lyricist has altered the spelling of a word to create additional meaning or context for the song.
You can also consult those around you about specific words and phrases and what they think these things mean. They may have knowledge about something specific in the song that helps you complete your analysis.
Finally, give yourself time to complete your interpretation. You may need to sleep on it, or give yourself a week or more to complete your analysis.