1. First time
Easy to get, just proceed with the story provided you did not molest her.

2. Morning sex
Required clothing: apron. Have Sylvie wear only an apron. Scenes trigger in the morning with Lust Low-Med-High.

3.Outdoor sex
Required clothing: sleeveless dress. Go out with Sylvie to the forest, then rest in the shade. (Some of the forest choices were not translated for me but you want the lower choice.)

4. Oral
Keep patting that head etc. and ask her for oral. The scenes will unlock with Lust Low-Med-High.

5. Postpone sex
Do not have sex with Sylvie for a while and she will eventually approach you. You can either accept (Scene 1) or decline her (leads to Scene 2 if you keep postponing sex). Repeat after she approaches you a second time for Scene 2 or lead-up to Scene 3. Lust Low-Med-High. The first scene should also unlock the animated extra scene.

6. Masturbation
Go out alone, then come home early. As in, do not go to the restaurant. First scene unlocks at Lust-High. You need an item from the first scene to get the second one (take her to bed while she is wearing it).

7. Nurse Sylvie
Required clothing: nurse outfit to unlock "Work" option. Postpone sex with Sylvie for a while, then work late. Scenes unlock with Lust High-Very High.