These things all help, but ultimately reduction of blunders is the result of consciously checking whether you're blundering something, not being a genius calculator. Most blunders in chess (outside of the higher-levels) aren't the result of failing to see some 5-move tactical sequence, they're just hanging a rook because you were hyper-focused on your own initiative. Controlling your blunder rate is IMO a game of attending to your own mental state: ensuring that you're giving proper consideration to your opponents threats, being realistic about your advantages, and preventing your imagination from running away on you. Obviously study and puzzles can help you do these things more effectively (for example making you more likely to pick up material when your opponent blunders), but they are a necessity not a sufficiency. At the end of the day 'not blundering' is about staying humble, playing slowly, and not freaking out; everything else is points on the margin.