making the right decision is based on the odds, or occasionally on reads.
You might have an oesd and a flush draw going to the river but if you dont have odds you cant really call.
Reads alter this slightly as sometimes you're hand may be good when it appears not to be, eg callin g with bottom pair HU after big bets from opp on low board etc.
Basically, if in your thinking and taking into consideration odds you can justify your play then it is the right decision play, if you cant then you learn why and dont do it again, or try not to.