Credibility is everything when you're leading a startup team--how else are you going to get employees to put in crazy hours at a venture that might not even succeed?

Knowing what you're doing and being well-versed in your area of expertise will get you off to a good start in building respect from your team. But you also need to avoid these common mistakes that will kill your credibility--fast:

1. Act like you know everything.

In my former working life as an IT manager, I remember compensating for my lack of knowledge in certain areas--usually, I'd use pride or even coercion as the stop-gap. If I wasn't 100 percent sure about some new-fangled network storage technology, I'd still pretend to be knowledgeable to make sure people still respected me. In the end, I was not helping my case.

There's nothing quite like a leader who can admit to being human, and a flawed one at that. You can't know everything about any topic. Your employees understand this. Saying "I don't know" is a sure way to earn respect.

2. Point fingers.

We all know this rule, and yet it is one of the hardest to avoid. Somehow, society in general decided that the "boss" is the one who points the fingers. Being in charge morphed into a role where you have to be critical of everything, but that's not exactly the best leadership trait.

When you constantly point out faults in others, you tend to create a negative vibe. Sure, at times you will need to correct an employee's work. But rather than simply point out what's wrong, come up with a solution so that your feedback is constructive. People are more likely to turn to someone with smart insights rather than the colleague with a sharp tongue.

3. Rule with anger.

I've seen this one at least a hundred in the workplace. The boss is the one who wins every argument because he or she has the loudest voice. The angry guy at the meeting is the one with the biggest paycheck, right? Unfortunately, it's a terrible way to lead--it makes the workplace uncomfortable for everyone.

More importantly, anger ruins your credibility. You become a time bomb. No one will really look to you for answers or for genuine leadership when they need it most. Instead, they will assume you are going to explode in the face of a crisis. Calm, reasoned discussions always increase credibility at work. Those are the leaders who, in the long run, attract the most followers.