Vocals are widely regarded as the most important element of the song.
Sidenote: >>> Seriously, for music nerds like us it is almost ungraspable how important vocals are to the average listener. Where we hear a killer snare or a great bassline, the vast majority of listeners just hears “the singer” and perhaps a “fun melody”.
That is not to say that making a good production, mix and master does not matter. All listeners will still recognise if it sounds good or bad. If you aim to receive reactions like “This sounds so good”, “This song massages my ears”, “This part sounds so beautiful”, “This song just lifts you up” and so on, the mixing and mastering of your song need to be on point! <<<
Since vocals are most often the most important element of the song it is best to place the lead vocal in the center of the mixing space.
Backing vocals often sound great when panned on the sides of the mixing space.
A classic vocal setup is a lead vocal in the center, one backing vocal on the left side and another backing vocal on the right side, like here:
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your vocals.
By using two different recordings of the backing vocal and place them on either side of the mixing space, you create a difference between left and right. This creates a very nice stereo sound for your vocals.
This is one of the most common setups, you can’t go wrong with this.
If you are looking for a more creative approach, try experimenting with different stereo placements of the vocals. Just make sure that the vocals have enough room to be clearly audible in the mix.