How do i unclog bathtub drain properly?

it's almost always hair. take the stopper out and fish it out with one of those cheap plastic barbed drain strips - gross, but it fixes it in two minutes. if that doesn't clear it, plunge it, but stuff a wet cloth over the overflow hole first or you're just pushing air out the top. then a kettle of hot water to flush. once it's clear, a hair catcher over the drain stops it happening again.