Improving my falsetto and vibrato?

what's the best way to improve it? i am an operatic b baritone and an amateur,i dont know about chords,but i can perfectly sing along an instrument...my vibrato and falsetto are good,but i need to improve them more,i mean,my vibrato is kinda slow and not so notorious unless i apply the falsetto,and my falsetto can't reach such a tenor chords,i am about to but then my voice breaks down....so,what kind of excercises do i do to improve them?