EASY THINGS THAT CAN IMPROVE YOUR SHOW IMMEDIATELY.
~Engage the audience. Don't take long looks at your phone or notebook for prompts. Don't stare at your feet or off to the side. Look around at the room and into the faces of the crowd. It need only be a moving glance, but do so. You may not want to engage each individual face but you want them to take a look at yours.
~Speak up, don't mumble. If they can't hear you and understand you it won't be funny.
~Get your first laugh as quickly as possible. It relaxes you and the crowd. Btw the first joke should be for the full room, start with some A material, no inside jokes to friends in the audience or at the back of the room.
~Don't down multiple alcoholic drinks before your show and don't hold one in your hand constantly. Get a full grip on the fact that stand up comedy is far more than just being a drunk smart ass.
~Add more energy to your act. Even if you're a deadpan comic you must exude energy. Btw, deadpan doesn't mean slow paced and no energy.
~Take responsibility for your show. Don't blame the audience for not getting your esoteric rant about how high you are. As a matter of fact don't tell the audience you're stoned, been stoned today or just got stoned etc. etc.
~Stay in the moment of each of your jokes. Don't think too much but feel a lot. (get on board the feel train!) Take care of the moment and the next will take care of itself. Don't attempt to cram in too much. I think the mistake of some comics and even many of today's sitcoms are they shoot jokes at you like a shotgun, whereas a great joke is like a single bullet and deserves to be given an enjoyment moment ;)
Energy is one thing, too much, too fast is another. I believe some TV producers think energy is the hypnosis behind television; and the way to hold an audience is to overload with awesome sets, colors, fast dialogue and quick moving images. I suppose that would work if you had cats in your demographic, nonetheless, it doesn't work for live audiences. Give your jokes their own moments, don't be thinking ahead too much if at all. Feel and deliver.
~Reveal a bit of your back story as quickly as you can. Tell the audience something about yourself...especially if it's obvious. If you're extremely overweight, very tall, very short, have a huge nose or ears, stutter or have any kind of speech impediment....tell the audience, point it out and move on. Again, revealing moments are usually compelling and tends to relax you and the audience... and when you're relaxed and so is the crowd, you can really let go and have fun.
~Watch your body language. Don't back up on punch lines. Movement should always favor your audience.... ;)
...move towards or with the audience, not away from.
Most importantly, have fun, I mean have real fun with it. If you're not having a blast you're doing it wrong!