In order of importance:
#1 You need a good vocalist who knows how to sing in front of the microphone
#2 You need a good microphone
(as you see, the 2 most important things need to be met long before mixing)
#3 In your mix, use EQ to “dig hole” for vocals on instrument tracks (cut frequencies, which are at the same frequency range as vocals)
#4 In your mix, use EQ to “dig hole” for instruments on vocal track (cut frequencies, which are dominant on instrument tracks)
#5 Use compressor to even out excessive dynamic variation of your vocal track (this is extreamly important, if condition #1 is not met)