I too have sent out about a dozen emails to new people visiting my 
caches...with about 6 responses(all very positive and thanking me for 
my email).  I've even had a couple people contact me directly from my 
personal (though very out of date) webpage to ask me about geocaching!
If they log a no find on one of my caches, I make sure to thank them 
and tell them how important logging no finds are to a cache owner and 
fellow cachers...then offer any assistance in finding the cache their 
next time out.

Team desertSol
Chelby & Kevin
+
Kiva and Lancer (German Shepherds)
Apache Junction, AZ
www.desertsol.com/~chelby/geocaching