Consent-o-matic automatically answers cookie pop-ups for you, so saves heaps of time. It also works fine on mobile if you load it into Firefox nightly with a custom collection.
In addition to what jayandp said, it can also be useful to correct some "bugs" if you know your way around CSS. For example something I really hate about the default Lemmy themes is that they stretch the videos to the full width of the page, so I made a CSS override to fix that: