Skip the stop bath. It`s purpose is to neutralize alkaline developer. Fix does the same thing at some loss to fix capacity. Since I do not use fixer more than one time, I don`t care. Normally I use alkaline fix so why go base, acid, base.
Always use fresh chemicals. Throw away old stuff. Silver precipitates in used fix and settles on the next film ( that is the black particles on the bottom of the bottle). Those are the white spots on the film.
Use an eyedropper or transfer pipette to get Rodinal from a bottle so you do not pick up the precipitate from the bottom.
Use glass bottles you can clean and always use the same chem in the same bottle. Label it.