First of all, s/he must accept others points of view as things to consider, and counter if you can. The thing that makes a BAD debater is to kick the opposing debater out of the debate by "banning" her/him from expressing that opinion, especially when they can't "debate" their opposing points. We have some bad debaters here, (not mentioning any names). ;-)

A good debater can approach the same issue from multiple angles and find the best way to translate their position in such a way that makes the most sense to the person they are debating.

A good debater can find ways to relate to the person they are debating with in an almost deceptive manner to make them let the "fire wall of bias" down and bypass the "me vs you us vs them" without resorting to dishonesty or compromising their views.

A good debater knows when to simplify things and when to deliberately attempt to confuse and impress the opponent with complicated terminology and overly intellectual statements in order to establish intellectual supremacy.

A good debater can debate with even the most difficult to deal with, such as fromwithin or nomenclature, and find ways to force them to use logic for once in their life.

A good debater doesn't engage in hyper reductionist strawman fallacies of douche baggery

A good debater is honest with both their opponent and themselves.

In my opinion it depends on how we are measuring a good debater. Appeals to ethos (credibility) and pathos (emotion) are often more effective than logos (logic) in persuading the listener. A focus on logos, however, is more likely to deliver an argument that is factually true and that the listener can understand intimately, rather than "feeling they have a rough idea".

I believe that, as others have noted, finding points of agreement is very important and often people talk past each other because these points of agreement have been ignored. I also think that the ability to get to the root of the disagreement, rather than arguing several steps removed from it, is incredibly powerful. These are two things that I really need to work on!

Finally, willful ignorance is often a problem in debates (and discourse in general) because it is so painful to be wrong, especially when one vehemently expounded the view moments earlier. When I was younger I would fall into this trap all the time and it really retarded my intellectual development. I personally try to moderate this effect by not being as zealous in my discussions, though I often fail in this.

A good debator is relentless, actually knows what they are talking about, doesn't blindly throw out fake news or nonfacts, and provides sources for everything they claim that isn't common knowledge.

- Even though a common standard for debaters is "using facts", it is also just as necessary to provide sources and statistics in order to substantiate your claims. If you can't provide reasoning and application to your claims, they aren't valid.

- Having the self-control to avoid resorting to emotion-based responses. What an individual THINKS about the world is not important. What facts, stats, and logic SHOW and PROVE about the world is important.

- Have humility and respect for the person you are debating. Accept that not everything you say will be correct, and that you can have a spirited debate without it being combative or hostile.

It's all about content...................................................................................................................................................................................................................