Depending on the arrangement of your song, the mix can start with different instruments. Sometimes you may start with drums, other times the vocal. One way I found is to decide what the song could not do without, then start there. Many songs could do without background vocals, so that may not be a good place to begin. However, if the song is a heavy, driving rhythm, the drums provide a lot of that feel, so that may be a good place.
Once a solid and unobtrusive foundation is laid, other instruments can be dialed in and fit in the mix. One thing not to do is leave the vocal till the end. You may find that there is no room left in the mix. When working with the other tracks, be sure to check the mix with the vocal so you are never surprised. Often times, instruments can be left out of parts of the mix or it may get too cluttered.
Once you get your mix built and sounding good, it's time to really make it shine. Often, the vocal is where this will happen. Too many people spend too little time on the vocal. This is what most listeners will pay attention to. Nobody is going to care about the .5db boost you put on the snare at 1.4 kHz.
Get the vocal right, and the rest of the mix will work better for it. Make the mix work for the vocal, not the other way around. Try automating the vocal EQ for different parts of the song. The chorus may need a different sound than the verses. Also depending on the vocal range, EQ that works for some notes may not work for others. This can be a tedious process, but will make the vocal sound professional.
No two songs are the same, and no two mixes should be the same. Spend time and make your songs as good as they can be.