Time spent on site / bounce rate

I have only started looking at these metrics yesterday (they can be found in Google Analytics) but having a month of data I can already arrive at some conclusions:

• Pinterest - I had 100% bounce rate and average time spent on site below 10 seconds. This means that the Pinterest traffic was completely void and useless. I paid 0.2 EUR for one click.
• Facebook - bounce rate of 75% and average time spent on site of 1 minute 24 seconds. I pay 0.5 EUR for one click to the page.
• Instagram - bounce rate of 57% and average time spent on site of 10 seconds. I don't pay anything for these clicks, they're purely organic.
• Google paid ads - bounce rate of 100%. I paid 1 EUR for one click.

For now I'm going to focus on Facebook and Instagram and channels and set Google aside. 

My goal for August is not to make any sales but to build up the site's social presence and SEO as well as to drive high quality traffic I can further analyze. For now it seems that Instagram and Facebook will be the best channels to achieve this goal.

Wish me luck!