A major part of showing respect is to avoid the trap of being hyper-critical. Don’t criticize the way your wife dresses, cooks meals, parks the car or walks the dog. You might think you are instructing your wife, but you are actually showing disrespect for the decisions you make.
Actions are just as important as words. Don’t make decisions that normally a married couple makes together. This shows you have no respect for her opinion.
Also, try to avoid certain intonations with your wife, the kind that can be described as “talking down” to her. A woman can pick up on these as well or better than a man can. These tell her you have contempt for whatever is she’s doing, that you are treating her like a child or even your pet. Showing a lack of respect is one of the surest ways to poison a marriage.