(Please see Wikipedia talk:Manual of Style/Accessibility § Listgap: a proposal)
Lists
editDo not separate list items by leaving empty lines or tabular column breaks between them. This includes items in a description list (a list made with a leading colon) or an unordered list. Lists are meant to group elements that belong together, but MediaWiki will interpret the blank line as the end of one list and start a new one. These excessive double line breaks also disrupt screen readers, which will announce multiple lists when only one was intended, and therefore may mislead or confuse users of these programs. Improper formatting can also more than triple the length of time it takes them to read the list. Likewise, do not switch between list marker types (colons, asterisks or hash signs) in one list, unless embedding lists starting at the highest level.
For example, in a discussion, do 
this best practice:
* I like this idea. [[User:Example]] ** Question: What do you like about it? [[User:Example 2]]
[BEGIN ADDED] which produces this:
- I like this idea. User:Example
- Question: What do you like about it? User:Example 2
[END ADDED]
or this acceptable practice:
* Support. I like this idea. [[User:Example]] *: Question: What do you like about it? [[User:Example 2]]
but 
don't do this:
* Support. I like this idea. [[User:Example]] :: Question: What do you like about it? [[User:Example 2]]
or this:
* Support. I like this idea. [[User:Example]] ** Question: What do you like about it? [[User:Example 2]]
[BEGIN ADDED]
Instead, you can use the HTML <br> tag to produce a blank line for sighted reading without creating problems for screenreaders, like this:
* Support. I like this idea. [[User:Example]] <br> ** Question: What do you like about it? [[User:Example 2]]
which produces
- Support. I like this idea. User:Example
- Question: What do you like about it? User:Example 2
[END ADDED]