I had a Ziebart undercoating done on my '72 just after i got it last 
fall.  It seems to be holding up well and I am pleased with it.  The goo 
is so thick and tough I can't get it off no matter how hard I try so I 
figure it will do an excellent job of protecting the underbody.  I don't 
know what these usually cost, I had a friend do it for $10. But I think 
that it would be worth a bit more.
	as far as tips, watch what they are doing.  most people have no 
idea what they are doing when it comes to old v.w's.  when they lifted 
mine they put the antenna right through the cieling mounted shop heater 
and busted it off.  If I hadn't been watching, that heater would have 
ended up in my front seat via the windshield.  The guys response to all 
of this "oops, I forgot these things dont have any hood". also, make sure 
they get everything; rear swing arms, inner rockers, etc.. They even got 
my heater tube and brake vacuume line.  if that doesn't stop any leaks I 
don't know what will.  It would probably be a good idea to make sure your 
front cover pan thing is in place, i imagine that all that goop on the 
bottom of your pedals would be bad.
good luck.
Ed.