On Sun, 23 Jan 2011 11:28:53 +0000 (GMT), JTM wrote:

Gentle tap tap tap with hammer and nail punch to chip through the glaze,
even the smallest dimple will reduce drill bit skidding.

Yep by far the best way to get the drill to start. Not a nail punch
that is blunt, use a center punch or sharpened round wire nail. You
can position the tip of the punch/nail exactly where you want the
hole and very gently break the glaze and enlarge the pit to take the
tip of a tile drill or one of those Bosh multimaterial drills.

Or, masking tape stuck to tile and start gently drilling through that

Never had much success with that the drill still wanders a little.

--
Cheers
Dave.