I'm not quite sure of the Pot Luck origin. (or Pot Lock as a former boss called it) I'm not quite sure if any luck is involved at all. I think it's mostly skill involved. Here are some tips.
First you have to get there early that way you can see whose bringing what, that way you can avoid dishes made by "you-know-who" Yes, it's a bit mean but it beats the alternative of sitting on the toilet for 3 days. If by some chance you get there late, you have to ask who brought what or the unavoidable trip to the porcelain palace will await you.
Secondly, do not take advice from anyone but your significant other. I was at a Pot Luck when someone informed me how good the "shrimp alfredo" was. So I got a huge portion. Yeah, not so good. Think Kraft shells and cheese with shrimp thrown in and you have the so called "shrimp alfredo." But what made it worse, was that my aforementioned boss had made it and that boss kept coming in there talking to everyone. I basically had to eat what I could of the stuff before a well placed napkin could hide the rest. I then waited for the perfect moment to dispose of it. I know it was a waste of food but had I eaten the rest it would have ended up in the trash anyway via projectile vomiting.
Thirdly, do not spend a bunch of time making a "new" dish or an odd dish that no one will eat. I once made a very tasty black bean soup that 2 people ate and I was one of them. If you make a dish that you've never made before, then how do you if it's any good. By the way, if it does suck, then you may be in line for the next "you-know-who" title.
Next, if you have to ask what something is, pass on it. If the person who made it can't make it well enough to make it look like is suppose to, then it probably doesn't taste like it either. Oh, it may be the best tasting stuff ever but I ain't chancing it. I suggest loading up on what you or your partner brought and play it safe.
Lastly, if all fails, head for the desserts.