I get you, the guide isn't the most descriptive in parts, however I managed just fine and thought the good choices were all together kinda obvious - not to step on anyones toes, I guess the answers just clicked with me...
For anyone still struggling all I can say is to pick the options that allow Rachel to do what she wants, encourage her to speak to her mum over her brother, agree to pay her extra over forcing her to do stuff, ask her how her life is going rather than focusing on taking your pictures, play along with her rather than outright refusing her during the eating activity, buy the extra costume from the mall and gift it to her & gift her a phone as well. There were only 2 times I figured I might have chosen the not so nice options and both times they seemed to extend the scene further than the other option so I stuck with them; once during the last stage of the massages I chose to tease her further & the other time during the final stage of the swimming lessons I asked her why she hated her brother instead of imgagining someone else.
Also the guide doesn't explicitly state when to visit the Red Maiden to get the mask so for anyone stuck at that point, talk to your friends in the bathroom and ask them, visit Red Maiden during the morning and get stopped, visit your friends in the bathroom again, buy the mask from the shady alley dude - it's a talk option, not a store option for him.