Bounce is 87 how do I decrease it?

I have always struggled with bounce rate and mine has now risen to 87%! Would love to hear some suggestions for decreasing it.

I started going through my posts a couple of months ago adding in internal links and improving the opening paragraph as much as possible and this starting bringing it down - to around 66% at one point. But now it's gone up sharply again.

I have found one of the big reasons for this. There has been a big increase in my referral traffic and this seems to be mostly from what, as far as I can tell, are spam sites (see analytics report below). These make up a reasonable sized chunk (about 25%) of my traffic for last month and the bounce rates on this spam traffic is close to 100% - and they don't spend long on the site so my average session duration has taken a dive too.

Now to my questions:

1. Is there a way that I can block certain websites from accessing my website (or at the very least have them not included in my analytics stats).

2. Even taking that traffic out my bounce rate is still around 72%. Can anyone think of anything else that I could do to reduce this (and increase average session duration).

I know that bounce rate isn't everything and that some bounces are even sought after (i.e. someone clicking on affiliate link) but I feel like mine is too high and there is something I can do to improve the website to keep people on the site for longer and visiting more pages.

Your help is much appreciated.

Nate