It depends on what you're recording on and what reverb you have. Can you give a little more information on what you're presently using?
I record my vocals dry into Cakewalk 9, and then I use the DirectX reverb plugin that came with Cool Edit 2000, and I get decent results from that. Fairly lo-tek, and probably not quality with a capital QUA or anything, but it doesn't sound cheesy either.
Generally, less verb is better. And like the guy above said, presets are a fair starting point but you usually need to go further. My favorite reverb from CE2000 is a preset called "Natural Reverb", and then I take the wet mix from 15% to 25%. That generally sounds pretty decent.
Also, is reverb the only effect you're looking for? I've found that a touch of chorus helps to make my voice less strident.
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David Vesel -- electro recording artist
The current single is "Numb" from the album Calliope
On Ampcast / Situation Records
http://www.ampcast.com/davidvesel
davidvesel@pobox.com