For advertising, I recommend fireviews, tumblr, and twitter. Social networking in general is a good idea. Word of mouth. Make some friends and promote each other's videos. Do some collabs.
For how you should act, I would recommend keeping your energy high and keep the action going. Whether you're talking or making a film, keep things moving. I always make the mistake of being too relaxed or being too shy. Try to keep your content original and unique without going overboard.
I always misuse annotations in my videos but that is part of my style and people seem to like it due to the extra humor it adds. Being a writer, it helps me to connect with people better. I recommend using them to link to reverent things you discuss in a vlog or to your last video if you do film or music or gameplay.
Play to your strengths and work on your weaknesses. Don't forget to enjoy making videos. When you like it, so will viewers.