Choose the best possible song to make your video. It should be well-crafted, well-recorded and have universal elements that will evoke emotional responses from a wide variety of people, not just your friends and family. If you don't start with a great song, it's much harder to make a great video.
Collect your visual assets. These can be photographs, digital video or a combination of the two. The song you've chosen to make a great music video for will elicit emotional responses from listeners, and it is important to choose imagery that will complement and even enhance that response. If you are cutting a video for a sad song, don't use happy visuals.
Add your images to the beat of the music. Just about every song has a defined tempo, a recognizable rhythm to it that you can identify. Maybe you tap your foot to the snare drum, or tap your fingers with the recurring bass line. Listen to the music, identify this rhythm and cut your footage to match it. The tempo of the visuals should match the tempo of the song - if you're making a great video for a slow song, you won't have any fast, choppy edits.