First off, the usb mic is probably not going to a good job of capturing the audio. Decent, but not great. If that is what you are stuck w/ find the best sounding room to record in. Put the mic in the rooms available and crank up the vol recording. Have a spoken voice, maybe some claps to get a sense of the air in the room. For home recording a small, dampened room will get the driest, and best sounding "air" available (unless you are lucky!).
As far as processing your acoustic recordings, voice in your case, it is a case by case project. But for voice, my usual chain includes the opto or fet (or both!) compressors in the ProChannel. Those are both good. The Sonitus is also good, has great visual feedback (so you can understand what the hell is going on) and is clean. What you want to do is even out the vocals (a little) so the quiter sections more closely match the loud ones. You should do this after volume automating the track. One thing it takes a while to understand is how too much compression will cause sibilence and your "th"s to get hard and raspy. Vol automation can help w/ this and using more than one comp (such as a little FET then opto chain as above) is smoother - more realistic. Once the vocal "sits" in the song how you want it, you can try some eq.
Almost every vocal can use some high pass filtering. Depending upon the voice, there is little going on down below a 100 Hz, or even 200. All there is down there is noise, thumps and other sound that eats into your headroom and mucks w/ your compressor w/o giving you any real information. Raise the filter until you can hear it bite into the sound, then back off your settings (gain and filter mode). You don't want the noise but you don't (usually) want something that sounds unnatural.
Hopefully at this point you have a nice, strong and fairly even vocal w/ no large dynamic shifts and sounds pretty clean. Even if your room has some reverb (and they all do) you probably want something prettier for your lead vocals. PerfectSpace is a convolution reverb that will add an imprint of differnet spaces. Find one that works for the song.
At this point you should have something workable. There are plenty of other vocal tricks as in the cake Vocal strip (which ain't a bad way to go, esp. if you are learning). After you can shape a recording some you'll start to hear tech problems. You'll invest in a better mic, better preamp, better convertors and room treatment and still hear flaws, but minor. Rinse and start again on hardware as you refine your mixing techniques. Working w/ your equipment you will find what works for you and your ear and develop a style - not so much in sound as in technique to get a sound.
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