how to tell on first pressing vinyl releases

I started some flea market and ebay searches and am perplexed on how to tell if an album is a first pressing release or a later release.

Also are less than 180 gram re-releases decent quality (think jazz reissues in the $10-15 range from Acoustic Sounds)

I did luck out on a two eye Brubeck Time Out and what appear to be first issue Jose Feliciano and Joni Mitchell discs.

thanks
Tom