Dilbert author Scott Adams has a nice post about how to seem smarter than you really are. Here's the best part:
It's important to agree with people if you want them to think you are a genius. For most people, the definition of smart is "Thinks exactly like me but even more so." If you think that disagreeing and offering excellent reasons for your thinking will change anyone's mind, you might be new on this planet. The best outcome you can expect from any conversation is that the other person will walk away thinking you're probably the CEO of something, assuming you also seem selfish, egocentric and unethical.
This is why sycophants sometimes end up as CEOs.