Knot tying requires some 3 dimensional imagination. Do a search of "must know knots." Start by learning bowline. Practice with eyes closed. Practice while watching TV or some other distraction.
A tree service worksite can be a fully encompassing hazardous environment. Sometimes, you must take your eyes off one danger to address another. Above, below, and anything from a swinging limb to a spinning saw chain can come at ya from the sides or suddenly behind you. Climbers will say to always look up and watch them, but if you walk into ground run rigging, stumble into a coworker running a saw, get foot tangled in rig line going up, or forget where the in ground pool is, you'll be in trouble. Gotta watch climber for instruction, his safety, and to know when load is coming on above, but full SITUATIONAL AWARENESS needs to be developed. Evidently, you also need to look out for crane operators swatting ya with a pick rather than fire you.