While you're speaking, look directly above the audience as opposed to making eye contact with everyone. You don't need to actually make eye contact if it looks like you are. As you're looking directly above the heads of the audience, scan the back of the room with your eyes. Avoid looking down at the floor, and avoid looking up at the ceiling. Engage the audience with your speech, don't just talk at them. Pretend you're at home practicing your best man speeches brother in the mirror or just talking to the Groom one-on-one. Although this sounds a lot easier to say than to actually do, it's actually pretty easy. Take a couple seconds before you start talking to gather yourself and get “in the zone.” Honestly, it's alright to take your time. No one will even notice. Five seconds might feel like an unbearably long time, but it's only five seconds. Give yourself a little ego-boost: you were chosen out of all the people the Groom knows to be his Best Man. Most people go their entire lives without getting to perform a best man speeches. You, out of everyone, get to represent the Groom as his best friend, father, or son. So be proud of yourself.