Its about 2 things - content and delivery. Content - this is similar to what davismwfi said i.e what you're saying actually has to be smart, and directly addre

Its about 2 things - content and delivery. Content - this is similar to what davismwfi said i.e what you're saying actually has to be smart, and directly address the topic very well. Don't beat around the bush, laser focus and say exactly what is required. Delivery - This is about confidence. Speak slowly, calmly and clearly, keep an upright, open posture and directly look at the other person. Expect that the other person will listen because you have something valuable to say (and the content should match this caliber). Speaking slowly, taking up space with your body, eye contact - all of these things signal assertiveness/confidence. You can work on delivery all the time, but don't expect to come off like Bond all the time because you have to know exactly what you're talking about, AND the other person has to believe that (very hard in subjective matters unless you've already established a great reputation) to pull that off. I think the delivery should match your confidence about the content - for example, if you sound super confident when you dont know what youre talking about people will eventually peg you as a bullshitter.