After more googling I found these two tutorials for hardware debouncing
http://www.ikalogic.com/debouncing.php
http://www.labbookpages.co.uk/electronics/debounce.html
The ikalogic site says to use R1 = 10 K and C1 = 100nF ceramic capacitor.
But if software debouncing is your chosen solution then Debounce Code – One Post To Rule Them All | Hackaday has a heap of routines to look at.