Before joining any community, you should make yourself aware of the rules. Den of Angels has a mission statement:
The Den of Angels forum is intended solely for the appreciation of Asian ball-jointed dolls (ABJD) that meet our criteria. Though we have an extensive Marketplace available to members, our focus is on being a community and resource for people to share and enjoy their dolls through photography, customization and discussion.
Keep in mind that there are many message boards available. Just because your doll may not fit in the criteria at DoA doesn't mean that it isn't a BJD. It simply means you should discuss your specific doll on another board. Does that mean you shouldn't join?
It depends. I think there is a lot to be learned on large message boards. Even if you mostly lurk, you can discover a lot of different tips and techniques, plus gain inspiration for your next project. But you must keep in mind that if your doll is off-topic, you need to keep it where it belongs.
Community members who are in good standing, have been online for 25 days and have made at least 40 posts may invite up to seven new members per week. Each of these is approved by the current administration as well, to prevent any banned members from rejoining.
If you don't know anyone already in the community, you may request an invitation to join. You can email membership (at) den of angels (dot) com. (Of course, make that into an email address--with @ and .com). See additional information here.
Once you join, I encourage you to check out the Newbie forum. Only users with fewer than 40 posts may start new threads in this forum. It's a great resource for new collectors!
I hope to see you there. (My username is alington!)