Mark Terry made some very good points in his comment Monday. My observations in this blog will often be high-altititude. Details are up to you, your agent, and your publisher to hash out. Remember the key word in "Marketing Plan": Plan. If you think selling is easy, give me a call. I'll put you on the phone with your first 100 calls to RV owners with a product that is, without argument, the best and safest trailer hitch on the road. On your first day, 100 people will laugh at you, slam down the phone, and tell you to get lost. On the second day, you'll call in sick. It takes years of training and experience before a salesman becomes really good at his job. Why would you think it'd be any different than writing?
My point is, like Mark says, you're often just saying "I exist" to someone who may never be in a position to buy your books. Then, the next time you call, they won't remember who you are, so you'll say "I still exist" and perhaps find out what the weather is like on their end of the line. You've heard this before in the writing business, and I'll tell you again in the sales business, half of your job is building relationships.
Your first call will likely end with you asking to do a book signing. Remember: start locally. Most beginning authors probably can't make a nationwide tour fit in to the budget, but I'd be willing to bet there's plenty of bookstores within range of your home to keep you occupied for a while.
Let me stress this again: work with your publisher and agent. One or both these people can get you started on the right foot. Show that you are willing to put forth some effort and listen to their advice. They know what they're doing. Really.
Okay, here's another tidbit for today: If you find a published author who's willing to do things like, oh, pop into your blog and give advice, hang on! Make friends with that person. Chances are you'll hit it off anyway. After all, you're both writers. This is also a good reason to join a group like ACFW or MWA. Both of these organizations are full of published writers who enjoy helping out the un-pubbed.