So easy to recruit junkies though, you just sell them drugs until they can't afford it, and they're with you.You can hire an advertiser for your whores at your computer. Also you need to motivate your girls (in all jobs) at least once a week, better twice.
Also, just from my experience, avoid using junkies in any of your jobs, they overdose and die way to fast.
That is also why i don't like drug dens. They do not make that much money for the short time they exist (until the girl dies).
You could make a save at every day end and reload if one dies but that gets on my nerves very fast, so i just avoid junkies as working girls.
Non-junkies and you need to do unsavoury stuff like threatening or kidnapping them, or just getting extremely lucky and finding someone who is willing to hoe for you.