Somewhere in here there is a guide for best massages, some of them are not 100% accurate but if you do the right path they may not even mind going past what they usually let you. You can see if you got to that point if they start trembling, I think at lower relationships you need to do it right at once or they stop just when the last touch for that would be.
Here's a 100% accurate list of their massage charts as of 996c:
Rogue ["shoulders","arms","arms","hands","hands","back","hips","back","breasts","breasts"]
Kitty ["shoulders","back","hips","thighs","calves","feet","feet","hips","ass","pussy"]
Emma ["shoulders","neck","neck","back","hips","ass","ass","back","breasts","breasts"]
Laura ["shoulders","back","arms","hips","thighs","calves","ass","ass","pussy","pussy"]
Jean ["back","shoulders","neck","neck","back","hips","ass","ass","pussy","pussy"]
Storm ["feet","calves","thighs","hips","ass","ass","pussy","ass","pussy","pussy"]
Jubilee ["neck","shoulders","calves","feet","neck","shoulders","calves","feet","pussy","pussy"]
At lower relationship values they'll still get irritated if you touch their breasts/pussy/ass, which lowers their lust, and they'll get angry if you touch them there more than once.
Edit: I just wanted to add the word MassageChart to this post just in case someone is using search to find it.
Edit2: Added Jubilee