Being played against their mom. It is critical for mom and dad to be united in the disciplinary strategy. If a child can run to another parent and find leniency, it tends to destroy the other parent's credibility. Never override your spouse's disciplinary decisions in public. If you have a disagreement, air it privately with one another. And try to share the child discipline role between both parents regularly.
Confusing roles. Don't feel obligated to get your child's consent for the discipline you impose. You are the parent and have the responsibility to discipline. Your word on a disciplinary matter is final and non-negotiable. As children mature, you can begin to share reasons why you feel as you do about things, but in any case your word is final.
Imposing excessive guilt. Trying to use a "head game" like guilt almost always backfires. "I slave my life away for you, and you can't even clear your dishes off the table (or put away my tools or ...)." If you make a child feel responsibility for things that go wrong in your life, you are not acting like a parent but like a codependent. Stay away from the guilt trips and just impose consequences.
Lecturing. This is a trap that I often find myself in. Pulling the child aside and giving them a monologue of all the reasons why some behavior was bad usually doesn't result in learning but resentment. A better approach to child discipline is a dialogue finding out why the behavior was not where it should be. For example, if a child fails to do homework on time, a lecture on the value of education is probably not going to result in a change of behavior. Identifying reasons why the homework was not turned in and then developing a plan to address the reasons is a more productive approach.
Comparing with others. This is another common mistake I see, and lived out on many levels. "Your older sister was so good at practicing the piano every day; why can't you seem to get it?" We might see this approach as reassuring and offering hope. But instead, comparisons just breed resentment. Maybe the older sister loved and had a talent for the piano, while the current child excels at something else and does not feel a passion for piano. The comparison really serves no useful purpose. Try to see each child as a unique individual with his or her own talents and strengths.
By being aware of these common mistakes in our approach to child discipline, we can perhaps see them coming and make adjustments. Finding better approaches like the ones suggested can help any dad become a better and more effective parent and teacher. And behavior will improve in short order by using techniques that work better.