Some of the better blogs I follow (not just travel) have other parts of their business besides the blog - could be books, seminars, photo print sales, etc., etc. Think first about your overall business model and strategy - is it really just about having a blog or will there be more? (And the "more" may come gradually)
A blog is a tool, not a business model. I totally agree with the others that it's content, content, content - quality content at that. Even then there are no guarantees. As with many such ventures, expect to not make any money at first.
You have a passion for travel, but passion doesn't always equal profit. What is your unique perspective or niche that you will bring to the table? Figure that out first. good luck!