Hi there.. a decent mic is the very first thing, followed by a good quality cable, plugged into a decent pre amp.. obvious I know.. but the amount of people who want high end results without the investment is huge..
Ok so we don't all have the cash to invest, but still we seek the quality, and fortunately there are some not too expensive options out there..
I would check out this mic
http://www.zzounds.com/item--CADM179 .. it is really good for not just voice but perc, guit, room ambiance etc too. (I find the Rode NT 1A really thin sounding in comparison)
Once you get your signal chain sounding good WITHOUT fx, compression, etc, you'll get much better results when and if you decide to add anything...
That CAD is a VERY god mic for the price.. If you can find one I'd definitely check it out.
Hd