What software are you using to mix? With the possible exception of Audacity, I can't think of one that doesn't have a compressor.
However, if you really don't have one, there are tons of free VSTs out there. A quick Google will find you hundreds but here's a site that claims to list the best. Best Free Compressor VST/AU Plugins! (I can't personally recommend any because I rely on the ones that are built into my DAW.
As for the sound, Farview has it pretty much spot on.
This is my exact method. Maybe 400-3khz. I end up playing with those numbers to see what sounds best. There's a lot of additional information in the 1k-4k area, so play with those numbers and see what suits the song/vocal.