Positive character traits are those one would be glad to have. For instance, people prefer having friends who are devoted, caring, considerate, and thoughtful. By the same token, employers desire workers who are responsible, persistent, punctual, self-reliant and work-oriented. The key to weaving a tale that makes sense is to choose character traits that best fit the character's personality. Suffice it to say, one wouldn't want to make a villain seem friendly and lovable.
Negative character traits are used to describe villains and antagonists. In the story of Superman, for instance, his arch-enemy Lex Luthor is known to be disrespectful, mistrusting, selfish, and insincere. He's the type of individual who doesn't feel any shame for his wrongdoings. Other characters can also have negative character traits. For example, many of Lex Luther's goons are foolish, clumsy, and outright stupid.
Character traits sometimes have a mixed connotation. Though intelligence is a positive trait, it could be a negative character trait, in that a villain who is highly intelligent is also very dangerous. On the other hand, a good character might be the jealous type only because of something she suffered in her past.
Skills go hand in hand with character traits. A character with strong organizational skills is intelligent, neat, and organized. A character with great public speaking skills is confident, sociable, and calm.
Like humans, fictional characters are complicated entities with many different traits and skills combined into one package. A villain is evil and dangerous, but he may also be intelligent and clever. Meanwhile, the protagonist of a tale can be adventurous and heroic while at the same time clumsy and a bit arrogant.