Okay so first thing your have to do is join all the clubs, (Zack's club is not needed for this achievement but is needed for another achievement). I shall put OrfeasDourvas solution for joining the clubs down below this one if you want to know their locations.
While in Chapter 7 we can go around and do a few things to ensure the clubs stay active.
You can check your map for the icons to show there's something important to do there as well.
Genesis Fan Clubs
For this one go speak to the lady by the railings near the fountain in Sector 8. She will talk about how the group is running out of money and ask you what they should do. Choose the "Merge with a Rich Club". After finishing talking with her, head on over to the Study group woman in Loveless Avenue and talk with her. After listening to her to talk, she'll agree to this. Once she's done talking, run back and talk with the woman by the railings.
Angeal Fan Club
Keepers of Honor
Also in Sector 8-Fountain is a little boy running back and fourth, speak to him and they will say how their mum is going on a journey. After the conversation go to the train station and speak with the mum who will be just in front of you. When presented with the dialogue options choose...
"A mother without honor is nothing but a monster".
This will make her see sense and return to her son. Once your able to move again, head back and go and talk to the mum, insuring that the club goes on.
Sephiroth Fan Club
Silver Elite
Not sure if any action is required, but in Chapter 7 after leaving the Church, I did go and have a conversation with the woman who's in the park behind the slide. You receive a email after the conversation.
But upon doing these actions you should be gifted with this achievement.
A quick run down of the locations to join these clubs is....
Genesis Fan Clubs
Red Leather
Available in chapter 2 till 7
In Sector 8-Fountain speak to one of the three women to the right of the fountain.
She will ask if you want to join, say yes.
Study Group
As soon as chapter 2 and as late as 7.
In Sector 8-LOVELESS Avenue near the back of the hub.
She will ask if you want to join, say yes.
You will get a mail for confirmation.
Angeal Fan Club
Keepers of Honor
As soon as chapter 2 and as late as 7.
In Sector 8-Fountain speak to one of the three women to the right of the fountain.
She will ask if you want to join, say yes.
Sephiroth Fan Club
Silver Elite
Chapter 5 only.
In Sector 6-Park, near the Church hub there is a woman hiding behind a structure.
She will ask you three questions. The answers are:
Masamune
Super Nova
Left-Handed
You will get a mail for confirmation.
Zack Fan Club
This one is highly missable.
In Chapter 6 only you get a mini-game defending Junon.
Make sure to get all 30 enemies with no escapes as I do believe this has something to do with triggering the fan club.
After that and before you move on to the boss, the cable car directly across and speak to Cissnei who will say something about disappointing your fans.
After returning to Midgar in chapter 7 go to the entrance level of the Shinra building and speak to the receptionist on the left.
After this will unlock...