definitely comes with practice. as time passes, think about how much strength your opponent is showing. not even necessarily "i think he has ak", but, does that bet seem like he really has a good hand, he missed and wants me gone, why is he betting like this? to me putting people on specific hands is only useful in very specific circumstances, but gauging how much someone likes their hand can be used all the time. you will just gain experience with what your opponents will bet like with certain hands, don't force it, just wait for you to start "knowing" he hit or missed. eventually you will be michael who you might as well show your cards to preflop.