First step, are you sure it's not working?

Scope probes can easily load an osc down to where it no longer can
run.  What I do, is to probe the crystal can, and set the sensitivity to
100mV/div or less. This is a cheap and easy capacitive probe.

Another way, is to use a shortwave radio to pick up the osc directly.

If it's indeed not running, check the basics.

Do you have a parallel resonant crystal?
Do your crystal caps return directly, and only, to the chip ground pin?

Are your crystal caps the right size?
This is determined by the crystal spec, NOT the pic!
See http://www.dvanhorn.org/Micros/All/Crystals.php

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.