In my experience doing social media marketing for small businesses, I have found that the 80/20 or 70-30 rule works very well. 70-80% of the time, try providing value in the form of what your target audience likes. (20-30% of the time, promote your e-tutoring courses outright).

Here's an example: We live in a big tourist area, the Smoky Mountains. If we're marketing to people coming to town, we have to do it nationally because the locals already know how great it is and they don't need to be persuaded - so forget the local market for now. So what do we do? We post gorgeous images of our local scenery. Do this enough times and people wonder who you are, they will quickly make a decision that they like you and could maybe use your service; like a cabin rental company or grocery delivery service for instance.

For your e-tutoring business, your images could focus on the results your courses will provide. For example, an image of a happy young person jumping for joy, with text that says something like "this could be you". This will make them wonder how they can be happy and jumping for joy, so they'll follow you to see more. Now, that said, it's important that you are marketing to the right people. Just posting anywhere to get attention is like trying to win the lottery. You need to find your audience.
Feel free to call me for more assistance if you have follow-up questions. Be sure to send your questions in advance, and share your e-tutoring website with me so I can better and more quickly respond to your particular needs. Good luck!