After every mission you go back to the apartment.
This achievement can be gained after you have completed the 4th mission and you have the Last Resort achievement.
Once you get back to the apartment after this mission Joker and Glyph will talk about a party. You need to choose the option to prepare it.
You will then be told to gather the party supplies. Leave the apartment go to the Silver Coast on the Silversun Strip. Go to the top floor and next to the barman will be the store where you can buy the party supplies for 100 credits.
Once you have done that return to the apartment and talk to Glyph. He will inform you that you can send invitations to your party guests at your private terminal. Go to the terminal and
select throw party. Glyph will then ask you which type of party you want.
Mingle with the guests and Glyph will ask if you want to change the tone of the party. Choose what ever you want and the continue to mingle.
Glyph will again ask if you want to make some changes. You can choose to do nothing, deal cards or make snacks. I chose to deal cards. As before mingle with the guests.
The last part is a group photo taken on the sofa. After the photo has been taken and the game loads the achievement should unlock.