Woohoo skill - the art of lovemaking. Edit
Sims can gain skill by masturbating, having sex, and even getting raped (if they have the Masochist trait). Sims with the woohooer trait gain the skill more quickly, and are more likely to accept propositions to woohoo. (I think Woohooer sims are also more likely to ask other sims for woohoo autonomously).
Exhibition skill - the art of displaying yourself. Edit
Sims can gain skill by undressing, striptease dancing (music source), performing kinky shows on the computer (some level required) and exhibiting themselves in conversation. Sims with the Exhibitionist trait gain the skill more quickly, and are more likely to accept propositions to shot parts of their body.
To progress from skill level 1 to level 2 (the skill is level 1, the bar is full, but won't progress) you need to send a 'fullynaked' kinky selfie to someone else. To progress from skill 3 to 4, you need a computer. From the kinky menu on the computer use the 'make a forum post with photo' option. Again, pick a photo with the name 'fullynaked'.
Eventually, your sim will autonomously make kinky selfies, but to do so manually:
1) Undress completely (your sim likely will only do so in a room with no other sims.) Kinky -> Exhibition -> remove top, bottom, panties and bra.
2) Click the mobile phone in your inventory or from the sim menu and choose Camera -> Take kinky selfie. You should now see a photo in your sim's phone with the name 'fullynaked'.
BUG if your sim has very low attractiveness, kinky selfies will come out as 'exhibition' photos rather than a 'fullynaked' photo. Exhibition photos cannot be used to advance the skill. To fix this temporarily change your sim's attractiveness to 10 from the sim's kinky menu with the 'Set physical attractiveness' option.
Help! My sim always refuses to send or post a kinky photo! Edit
OK, here are some tips.
- Get your sim extremely Horny. Buy some hard-rock pills from the grocery store or order them online, take the pills every couple hours until the sim has the extremely horny moodlet.
- Get your sim drunk. Get a bar, and from the make... menu there should be alcoholic drinks like whisky or beer. Drink a whisky or a couple of beers to get them drunk. Do this while they're horny for the strongest effect.
- Have a max relationship with the recipient. Make sure that your relationship bar with the person you are sending to is near it's max.
Most of the time, this should be enough to get your sim to send or post the kinky photo.
Finally note that whom your sim is attracted to (according to KinkyWorld's system, not the romantic 'consider attractiveness' system) has a very large input on whether or not your sim will send the photo. So if all else fails, try to send a photo to a few other people that your sim knows, there's a chance that KW considers that random sim high in attractiveness and let the photo send.