I don’t even make flows that long, but I already have a list of tricks. These are the things that make working with Flow easier. Especially if you want to adjust them later on. Start with saving the input in variables is one of those tricks.
Immediately at the start of your flow you start by initializing variables and saving the input of the flow in there. Later in the flow you then only use these variables. The big advantage of this is that it is much easier to adjust the trigger later. You can then change the trigger and only refill the variables at the beginning with the input of the new trigger. You do not have to make any further adjustments in the rest of your flow.