Which LP pressing is best?

I am starting to scour ebay and elsewhere for lp's. Obviously, condition is a major factor (as is a thorough wash), but there are better and lessor pressings for many (most?) lp's.

Besides buying several and listening, is there any general way to predict which is better -e.g., first pressing, etc. Is there anywhere out there in cyberspace that might have this people's opinions re this? Is there any way to track an album's pressing history? Can I ask any other very obscure questions? :)

Thanks, Chuck