Probably the most important part of character development is the character's personal history. It's this history, more than anything else that shapes who the character is and how he or she will react in a given situation. I know that many people don't like to take the time to sit down and write out a character history but I believe it's critical. If you want a character that's one to remember and fun to play this is the best place to begin.
Equally important is that the DM read the histories. As a DM I love to get character histories from my players. I have built great adventures based on the information contained in those histories. This is also good information to have so that you can reward your players during adventures.
Example: Maybe instead of giving Grog that +1 sword I will have him find his long lost father.
What a great premise for an adventure! As a DM you will also find that knowing what your player characters value, is a great way to get them to go on a quest.
How do I begin building a history?
Take stock of your character and begin to build a history around your scores, skills and equipment.
Example: If Grog has a 17 strength, how did he become so strong? If his secondary skill is forester or woodsman, who taught him how to use a sword? Is it more plausible that he would use an axe?
That is all there is to it. As you begin to put the facts down on paper you start to build a framework for the rest of the character's story.
Using your framework you can begin to ad background details that will fill out the history.
Example: Okay, so Grog is a woodsman who uses a sword maybe his uncle was in the military guard and taught him to swing a sword or perhaps he was kidnapped by a band of roving Orcs and forced to fight for their entertainment. It was either, teach yourself to use that sword or die.
I think you get the idea. Before long you will find that you have a character with a lot of depth and all the skills and attributes you wanted. You will also find that this very same history will help you develop character traits that other players will appreciate and remember
Example: Because Grog was kidnapped by Orcs he hates them with a passion and will attack them on site. He also has the table manners of an Orc!