Every producers nightmare begins at lead vocals mixing stage, well not because it is not fun but because it is the most crucial part of the track. Here are couple of things you need to consider
1. Is it loud enough? If you have ever seen the TV show "Empire" you will hear Cookie Lyon go on and on about the vocals sitting on top of the mix and damn is she right. You want your lead singer to cut through the mix, you want their voice to sound as powerful as possible and yet being within the mix. Unless it is a grunge/rock track, it is most desirable to have the vocal every so slightly louder than the rest of the track.
2. Compress it: You might have recorded the vocal in several takes, some takes might be louder than the others. There is usually a lot of unbalance on the vocal track - you want to fix this with compression. Here's a tip: Try using parallel compression on the vocals to add an extra "punch"
3. Backing vocals: Backing vocals can not only make the lead vocal pop out but also make the entire track sound extremely polished. they are not only fun to mix but also place emphasis on the lead vocals and the words or parts that you want to lift in the mix. A high backing vocal on your hook can instantly make it more audible. It is also fun to play along with the arrangement and bringing the backing vocals in and out. Here's an example of building up your track with the help of BVs: Try to have no Bvs on the first chorus but add some of the 2nd chorus and add a lot more on the 3rd. Backing vocals are extremely fun to mix, so play around with the sounds and see where you can go
4.Double track:Twice the lead vocals, specially in the choruses bring out the best in the track. It gives the voice a depth, specially if both the takes are EQed differently.
5. Play with effects: Some of the most interesting arrangements can be experienced when the vocals are manipulated to create weird sounds. Tip: try playing with pitch
6. Break the rules: Rule number one is to not follow any rules! So Try something new guys! Invent!