agreed w OP, ill add some:
1. get a nice laptop bag. dont carry a backpack or one of those dumb vinyl "targus" or whatever laptop bags. if you want to lvl up, get a nice leather piece
2. posture. carry yourself like an adult, situp in your chair, dont slouch. i am often guilty of this.
3. body language. engage people by looking them in the eye, at least every so often during a convo. use their name during convo. people love hearing their name.
4. maintain proper frame. modulate your voice properly, dont get too high or too low. don't let someone else's tones or inflections knock you off your game or influence you. carry your own internal "metronome"