When you're new to the industry, it can be a bit stressful trying to figure out what is and isn't a good idea. I would be cautious of any site that guarantees more followers or gives you over the top promises (at a price) to promote your book. I've personally never paid for any of these services however, I have had them approach me repeatedly over the last few years. I also would avoid giving books away in exchange for reviews because even though people may agree to help you out, in my experience, many don't follow through. I also wouldn't recommend you pay a large amount of money....well, for anything, really. There are lots of free resources that I would try out first and see how it goes. And speaking of which, here is my list:
1. Press release. Don't know how to write one? Look it up online. Who do you send it to? Everyone you're inclined to contact. I would definitely send it to your own, local media, all free newspapers and places that deal with writers or the arts. You may or may not get a lot of bites but regardless, you're showing off your new book and you never know who's paying attention.
2. Social media. I think that is a given. I personally am having a love affair with Twitter, however, I also use and enjoy Facebook, G+, Instagram, and Linkedin. Make sure you post regularly, reply to comments, shares etc and be consistent.
3. Create a website. It can be super professional but there are also a lot of free sites out there you can try out. It simply gives people a way to find you online.
4. Try to get your books into libraries especially the one in your area.
5. Join Goodreads. Not only can you add your books you can also share what you're reading too.
6. Get reviews. This is often easier said than done but it definitely helps you out.
7. Work with other authors. Sometimes you can exchange books to write a review for each other. Of course, you can always be creative and think of other cool ways to help promote one another.
8. Videos. Youtube, Facebook....talk about your book so people can learn about it. I would also recommend writing a blog. This gives people a chance to learn what your book and about you too.
Of course, these are just a few ideas off the top of my head. I also know that some people like to introduce their book in library events, book launches and more. It really depends on the kind of book you have and what inspires you!
The one thing I spend money on is having bookmarks made. I include images of all my covers as well as my website and social media. This is a terrific way to connect with new readers and who doesn't love a free bookmark?