great advice from duski on the workflow. the only thing i would add to make your results even more consistent is to use the same hitsound when finding offsets. as you run the playback at 25%, it helps to line up the beat in the music with a familiar hitsound (optimally one with a high-attack waveform like a drum kick)
also, some advice for outside of the workflow itself; make efforts to optimize your setup to be as low-latency as possible. aka wired headphones instead of wireless or, god forbid, bluetooth. in terms of software, windows is pretty limited in what you can do to reduce audio latency unfortunately; however, linux really excels in this department.
