I am an IM guy with 10 years of experience but honestly, I haven't done adult marketing specifically. But I will say that defining your target audience through some data is going to be your first step.
It is indeed a lot of hard work but hard work fetch you nothing if your marketing plan didn't define the target audience for you. I spend 80% of any marketing on this.
Yes, horny guys can be defined this way
I just checked Femjoy and it is impressive. It has 45K plus links indexed on Google and it received 15,000 engagements from Twitter in the last 30 days.
They use Hootsuite. I can give you a better alternative: Buffer. Apart this, I really can't say much without knowing about your business.