I think you always have to want to keep in touch with the fact that, as far as I'm concerned, I fundamentally suck. My agent is a real sweetheart, and my editor is a prince of a human being, so I'm very lucky in that respect. I haven't done any big book tours yet, but only in my hometown. You just can't think about it. You have to get an agent.
Agents are really the gatekeepers of the publishing world.
125 agents personally rejected me over the course of three years. Once I finally got an agent, he sold my first book to Warner Books in a month. My basic advice is to just keep looking for an agent, and don't give up. I was very tempted to give up after 125 agents had rejected me. That seemed like plenty, but you have to just keep going and looking, and not quit.