Assuming [5E].  At least 2 schools of thought and it depends on your desire for the game.  If you are a story player, who cares what the combination is so long as it makes good story.  If you are crunching numbers (referred to as min-maxing), most folks seem to start picking their class (how they want to fight/features they desire for their character), and then look at which race supports it the best.  There are no "wrong" ways to approach it.

Monks are generally focused on WIS and DEX.  They also tend towards a lawful alignment.  Tieflings get bonus' in CHA and INT, and tend towards a chaotic alignment.  If you are looking to pick up the best WIS and DEX bumps, consider wood elves, halflings or humans.