Removing white space

I’m tweaking my new WordPress site and would like to remove the white space which adorns posts.

Here’s an example: http://thebeachballer.com/2015/09/04/apple-music-ui-what-the-fuss/

The gaps bothering me are:

– between the header and ‘posted by’
– surrounding ‘filed under’
– surrounding ‘previous post’
– between the comment section and footer

It’s all a little too spaced out!

Could any of you lovely helpful people give me a bit of guidance on what exactly I need to edit?

Thanks in advance 🙂