I'll take the specific example of a bibliography. Here's a MWE to work with (the class is arbitrary here. I took it from some real papers on arXiv, and modified it to show the main things I want to concentrate on) :
So, should I use
\(for a space) as shown in this example ? Or use
~instead ? Or somehing else ?
For a change of paragraph in text mode, Should I use
\\(I believe this is obsolete), or \par, or \newline (or even something else) in the bibliography?