In my opinion, the best way to mix a track is by starting with rhythmic elements like drums and percussion and slowly moving on to more melodic parts. For example, this is the order in which I carry out my mixing process: 1) Drums 2) Extra percussion (shaker, tambourine, hand drums, etc.) 3) Bass or other low-end elements 4) Guitars 5) Keys, synths, other melodic elements 6) Vocals