Well from the tabs, that's hard to say... they don't show you the rhythm and timing of the notes so you'd have to know the song well.

But from ear you can do a little excersize I like:

Play a few notes here and there on the guitar to get your ear "warmed up." Then pick a string and a fret and try to hear the note in your head before you play it. Get used to anticipating what the note is going to sound like before you play it. The maybe play like an open high E followed by a G on the third fret. Now you have a minor third in your head. Play an A on the fifth fret and try to hear the 8th note C in your head before you play it.

Do this here and there throughout the week and your ear will really start to strengthen up and your playing and improv will start making leaps and bounds as you get good at hearing entire parts in your head before you play them.