Getting your blog seen by the world can be a struggle, but it can be done for free. You just need plenty of time and patience! Paying for traffic can get your site viewed by thousands of people very quickly. To do that with free marketing, you need the power of Social Media.
Social Media Marketing (SMM) is all about "sharing" - which basically means posting your own content, or copying someone else's text, video, or photo. You should be aware that most photos are owned by the photographer or someone he sold the rights to. Never assume that a picture is free to use, just because you found it on a well-known website. The same goes for videos and music. Generally though, if you're promoting a product, then the manufacturers or brand owners are usually happy to have their photos and logos spread around as much as possible. As long as it is not offensive or associated with anything unethical.
Anyway, copyright rant over....
If you're just starting out in marketing, then it's a good idea just to focus on one or two areas; maybe Facebook and Twitter in this case. Get good at those, and then start adding the others, like Instagram and Pinterest. If you do want to start with guns blazing on all accounts, then it'll be a good idea to automate some of your posting. For a free option, go to IFTTT. Look at the "Recipes" available; one that I use posts my Instagram photos to one of my blogs, for instance. Those photos go to Tumblr at the same time.
To build up your audience, it might be a good idea to keep some of your social posting very specific. If you like chocolate and coffee, then posting about both of those may put off the chocolate lovers who hate coffee! Think about what makes you "like" and "follow" other social accounts. I like to see posts about classic cars, but don't follow people who post too many modern cars, even if some individual posts are quite good. Then I just "like" each post.
There are many other types of free advertising, such as banner ads, classified ads, safelist emails, and good old Google search listings. Using some of these as part of your marketing system can build up useful extra web traffic. All these methods need plenty of effort and persistence, which eventually pay off with you having a big audience, and a big wallet to match!