A Dilbert comic has the titular character asking Dogbert for dating advice. Dogbert replies, "Try to be less like you."
As writers, we tend to project ourselves onto our characters. And why not? It's an indirect way to share our interests, likes, dislikes, etc., without (hopefully) being intrusive. Also, creating characters familiar with the same things we are allows us to remain in a comfort zone of sorts. No surprises.
But is Dogbert's advice something we should consider? I say "yes."
By forcing our characters to adapt to our standards, we're working within a limited range. Now if we apply the same traits to all our characters, well, you can see where the problem lies. The characters will most likely end up carbon copies of one another. If not for the characters' goals, we might not be able to tell them apart.
Am I guilty of doing this? Hell, yeah. It's a habit I'm trying to break. In my current WIP, I'm reworking my character charts, trying to make each character different and "less like me." My hero Zaphkiel tends to be analytical whereas his lover Caliel is more artistic minded. Actually, this dichotomy doesn't seem that strange to me because I can move back and forth between both thought processes with ease. Now Raziel is more mechanically minded and I can't hammer a nail without the threat of bodily injury.
Another way to create a character unlike you is to have him or her embody ideas or beliefs you may not agree with. This requires opening your mind and being receptive to new ideas. For example, you might cater to a Liberal point of view but have a character who chooses to see things from a Conservative viewpoint. Or a character who is Christian whereas another is atheist.
But whether you choose to people your books with characters who are just like you, somewhat like you, or not at all like you, keep in mind actions, beliefs, etc. have to fit that character's personality. You can't pick and choose traits arbitrarily. For one, character motivation won't make any sense.
What tips and tricks do you use to make your characters different? I'm working with Anne Olwin's character charts and sometimes I have to dig deep into my mind to answer some of the questions listed. :-)