it depends on who you know..with literary agents. You could join PEN or a writers association to establish contacts.
Shop around. Dont do it all yourself, it takes a team to publish a book. And another to sell it.
Book tours come after the launch of a book. But you have got to have the goods. Its no use writing something, then not bother promoting it or keep on writing and expect to just make a living off ONE book.
You have got to have it in you to write an entire series.
Maybe even a book every 3 months.