A good way to improve on ear ,is listen to black sabbath tunes.very easy to figure out, thats what my old teacher had me do. Cause most of all there songs ,are barr chords 5 chords.same chords different chord progression..maggior that was great advice,on keeping Guitar on hand while watching tv.and try and play what ur hearing.when i wacth tv ,i always have a Guitar in my hand, and do the same thing u we're saying, and if i hear a chord progression

Ill solo over it,once i find the key,by usein bass lines ,like u said..G3.