Pick the .htaccess Rules You Need
Open a group, tick what applies, and watch the file build itself. Start from a preset if you want a sensible baseline to edit.
How the Generated File Is Put Together
Order matters in an .htaccess file, and getting it wrong produces bugs that look random. Rewrite rules run before caching and header directives. Inside the rewrite block, a whole domain move comes first, then the https redirect, then the canonical hostname, then your individual redirects, and a front controller such as the WordPress block goes last because it swallows everything left over.
The generator sorts all of that for you, so you can tick options in any order and still get a file that behaves. Each block is wrapped in the IfModule guard for the module it needs, which means a server without mod_expires quietly skips the caching block instead of returning a 500 on every request.
Before you upload
Back up whatever is in your web root now. Download a copy rather than renaming the file in place, because .htaccess.bak sitting next to it is still readable over http. Then upload, load the site in a private window, and check the redirect chain rather than the final page: one hop is right, two or more means your rules are arguing with each other.
The setup guide walks through that process properly, including how to tell whether Apache is reading your file at all. Quick questions such as 301 against 302, or www against non-www, are answered on the FAQ page.