First, look your coworkers in the eyes and put your phone away. There is nothing worse than feeling like you're getting 50% of someone's attention. And, if you actually engage in conversation during meetings rather than scrolling through Twitter, you might come up with a killer idea.
Asking for help doesn't mean you're weak, and faking it when you're totally lost is never a good idea. Luckily, I've always had respect for someone when they were able to admit they didn't know the answer, so long as they did their due diligence. It's a huge sign of confidence, and you can't possibly know everything. I knew nothing about camera cars when I started directing driving shots on Veep; I asked the crew so many questions, and with each answer, I became more confident as a director. Your colleagues would always rather you ask questions than do something incorrectly multiple times.
Nothing beats laughter when you're trying to break down walls. There's comedy in even the darkest of times, and through laughter, we connect with one another.
Be Heard, But Remember To Listen
Speak up — and that doesn't mean start yelling. Being loud does not mean you're confident; it just means you're loud. But, because both men and women have a tendency to talk over each other and interrupt, it's important to stop, listen, and wait for the to the person to finish what they're saying. Never, under any circumstances, let people talk over you — no matter their gender. If someone repeatedly interrupts you, just finish your thought while speaking at the same volume. They'll look like the real jerk if they continue to yell over you.
Say please and thank you, but never apologize unless you've done something wrong or made a mistake. Own it and move on. Real confidence is admitting the mistake and making sure it doesn't happen again, and kindness still goes a long way.
Be A Student
Do your homework and take notes. If I have a meeting, I make sure to read up on the people attending if I don't already work closely with them. Sometimes, I find out we have mutual friends, or perhaps they did a project I love. Other times, I find out that we worked together before and it didn't end well. That's always tricky to navigate, but at least I wasn't blindsided by it.
Say what you mean, and mean what you say. Ask for what you want. Don't waste time wondering why someone didn't get the hint; instead, just tell the person. In my experience, most people want to help others. They just need to be asked something specific, and within reason. If they don't reply honestly and kindly (hello, tip number five!) then don't waste time on them.
Be Thankful For The Job
If you ask me, ego is a bad word, and conceit doesn't equal confident. I'm thankful every day that I'm working. And, even if you're not about to thank your boss, be grateful for the opportunity.
Be Supportive Of Your Coworkers
Confidence does not mean you have to be competitive. As you try to get ahead and be noticed at work, remember those people around you are attempting to do the same thing, Still, that doesn't mean you can't support each other: Stay away from gossiping and trash talking your co-workers, since it'll only reflect poorly on you.
Let's face it: No one wants to be around the complainer, or the person whose glass is always half empty. If you're always bitching about your job (and your life), eventually you'll be eating alone at the lunch table. Then you definitely won't be feeling confident.