Learn English – Do parentheses need spaces either side

According to Wikipedia there is no consensus on this in English:

There is no consensus as to whether or not to include a space between the number and percent sign in English. Many authorities prescribe that there should be a space, whilst others advise against it. The brochure of the International System of Units declares in chapter 5: "a space separates the number and the symbol %". The ISO 31-0 standard also specifies a space, and the TeX typesetting system encourages using one. This is in accordance with the general rule of adding a non-breaking space between a numerical value and its corresponding unit of measurement. However, style guides – such as the Chicago Manual of Style – commonly prescribe to write the number and percent sign without any space in between.

You have your choice. The white space goes either between paragraphs, or else in front of them, but probably not both.

Version 1, common on the Internet:

I am not fully sure if this is the right place for this question but I am guessing has something to do with structure and usage so hopefully it is alright here. Apologies if not.

I am getting confused when I write long reports and essays about when I should be writing paragraphs with a space separating and when I should have them following one another without a space.

I have been putting a space when it looks like too much of a wall of text but I am finding that paragraphs without spaces between them, look a bit weird.

Is it just when you start talking about something completely different that you should put a space, or should they follow on too? Should the space even be there or is it just something people do?

Version 2, common in print:

          I am not fully sure if this is the right place for this question but I am guessing has something to do with structure and usage so hopefully it is alright here. Apologies if not.
          I am getting confused when I write long reports and essays about when I should be writing paragraphs with a space separating and when I should have them following one another without a space.
          I have been putting a space when it looks like too much of a wall of text but I am finding that paragraphs without spaces between them, look a bit weird.
          Is it just when you start talking about something completely different that you should put a space, or should they follow on too? Should the space even be there or is it just something people do?