I read the other day that 10% of your time should be spent on marketing. If you divide that out into a weekly basis, it averages to just over 16 hours a week. That's a part-time job in itself! Not to mention all the writing we have to do and real life stuff, as well. But it's not so much to dedicate when you look at the results.
I have found that the more time I put in to marketing a book, the better results I get (usually). There are cases where that's untrue, but you never know until you try.
We've seen a decrease in participants for blog tours over the last year, bloggers not posting after they've signed up, or not signing up at all unless you're a "BIG NAME." I know how frustrating it is. I'm no where near big name status, and my salary for 2014 is about 68% of what I made last year. It's never fun to get a pay decrease when you're actually working more than you have previously. Don't let that get you down, though!
Authors across the board are seeing a decrease in sales and/or rankings. Thanks to new algorithms on Amazon, rankings are a joke and people must sell ridiculous amounts of books to make lists like New York Times. The number of sales required to make those lists have increased exponentially in the last year. Many of us are struggling.
So while there are an infinite number of ways to market your book, don't lose faith and don't give up. Something out there will work for you!