I think there are a few key factors in making a good character. This is one of the better questions of the last few days! But I might only be saying that because it is easier to answer than some of the others we have had in the last week or so.
Making a character is not just about picking the right skills, feats and equipment to give to the right set of stats. I feel that if you’re going to make a good Character you have to like it yourself. You could make the perfect combination of stats and skills, yet if you do not like what you have made you will not enjoy yourself.
The character must fit in the group. Playing a solo act is great and might sound like fun. But you will quickly find that you will be bored at the table as the story is going to focus on the players that are working as a team far more often then it will shine the spotlight on you.
The Character needs to have a reason for what they are doing. Your character needs the motivation to put themselves into the situation that they are going into session after session. If they have no motivation or drive. Why would they keep doing it ?
The Character needs to make sense. Do not bring a Pirate into a game taking place in the Himalayas without a DAMN good backstory!