Well Ash, welcome to the board. I think every singer and every person who ever mixed a track with vocals has had the same problem, and asked themselves the same question. Do I need another mic? a different preamp? What FX can I use to get that phat sound?
It starts with the source track. There are 2 major ways in which people mix vocals. They either mix the vocal track like an instrument, so it sits, as you say, in the mix. It sounds great but no one got the words. Or- they think the singer is a storyteller, and the words are more important than the perfect sonic balance. All vocal mixes are one or the other, or some compromise between the two.
As I said, it starts with the source track. Some mics just don't work for some singers in some mixes. The problem could be mic or preamp selection, but as they say, a shoddy workman blames his tools. You have to first try to get good sound with whatever tools you have. Good mics really do help make it easier to find good sound. Listen to the room. When you clap your hands, can you hear the echo? Once you have that source track, the heart and soul of mixing is EQ. Get the best hardware or plugin you can afford, if you're going to do the mixing yourself. When you start EQ'ng the vocals, you'll see whether you want to make the singer an instrument or a story teller.
If an instrument, you'll shelve unecessary frequencies that fight with other signals (guitar, keys in particular) for sonic space. By reducing key crossover frequency bands, each signal gets its own place to live, without competing for space in the mix.. This pulls the signals apart, so you can hear each of them better. If you think its a story (everything from "American Pie" to "Stairway to Heaven") The vocal often gets a little midrange boost, and *nobody* gets to use its frequency range. For this version, you'd better have a pretty voice (Faith Hill), a very good story (Bob Dylan), both of the above (David Wilcox), or just have style (Alice Cooper).
Often the backing vox gets treatment one, and the lead singer gets treatment two. How much treatment two is in your face, or toned down, is part of the difference between Tony Orlando and Dawn, Abba, Billy Joel and Ray Charles. There is a fine thin line between cheesy pop garbage and greatness. It is the ability to use both tratments well together that results in stuff like The Beatles or the Beach Boys. First, make sure you're recording in the right place in whatever room you have, and then treat the room in whatever way that particular room needs. Good Luck-Richie