Take my advice?

Alright, seeing the negative comments i think we need some clearing up to do. This game is very addicting actually.
The tutorial helps (when you start the game before clicking game start there is an option)

Waist size issue: Use your brain and eyeball it, there are differences~!
Some are very wide (literally does not fit the pants) aka chose the last option with the highest number
Very thin chose the first.

Happy are not?: See those hearts? That is their happy level the higher it is the more happier they are. Get their waist size wrong, chose the wrong wrapping will decrease a heart. Or if you wait too long then it goes down.

To increase it: Wink at the males and flatter the female.

Wrapping presents: Simple, just make it match exactly flip through and see what i mean.

Bottom clothing rack: that make you chose the clothes: flip through for the four stared clothing.

Person in dressing room thinks of a clothing on a mannikan: DO not drag them you are wasting your time it does not work~!
Go to the mannikan with the clothing and pick up the clothing then bring it to them.

Forgive any grammar or spelling mistakes Ive made since i sort of speed typed this.

Deletris about Jean's Boutique, v1.6