I'm interested in running the game this summer but I wanted to know what the rules meant by pre-new game manipulation (just so I don't accidentally do it or something). I'll be running on an Xbox One.

that rule was made mostly for not swapping disc at the start of the game to be able to have weird stuffs happen in the game, u shouldn't worry too much about it.

also always start attempts from a hard reset. some ram values, for example some of the steproute, don't reset properly without it.

A hard reset being just total blank saves? I dunno what the steproute is or if I plan to do it; I was just thinking of doing the Any% for the One/PS4 version.

Hard resetting means to restart your console

I don't think you would need reset the console for an Xbox run, just close the program. But its probably a good idea to anyway.