you can get a great sound through a good pre amp and mic. you dont need a booth to record vocals, their just easier to track when you listen to them through monitors and not headphones.

make sure your computer is as quiet as possible so you dont get a hum in your recordings, oh and use good cables.

I know my mixer has "preamps" but being as uneducated in the subject of recording I am, I don't know if the preamps need to be turned on or are always working when I use my mixer, anyway, thanx for the response

If you are using the xlr's on your Mixer, chances are you are introducing the pres. Otherwise, use the balanced outs....

I dont have the best mixer, but All I use it for is to monitor my recorded sounds. (Playback only- does not sit in the rcording chain.)

A few practical pointers;
Place the microphone near a corner of the room, facing into the corner. Have the singer standing between the corner and the mic, obviously facing the mic.
Put some foam tiles on the walls in the corner, to reduce the sound reflection off the walls. If foam is impractical, temporarily hang up some duvet covers or similar absorbent material.
By doing that, you will minimise the amount of unwanted sound reaching the mic.
If possible, fix a pop shield to the mic, to reduce the risk of 'plosions.
If possible, feed a little reverb into the singers headphones, but not into the recorded track. This usually helps to improve the singer's confidence. Be careful though, as some singers tend to sing sharp with reverb.
Don't record with reverb on the vocal track, and if you really must use compression, keep it subtle .. you can't take out what you've recorded!