There is a lot of work (both in thought and in actual preparation) that is involved in launching your own membership site. Of course, regardless of what you may have heard, building and launching your very own membership website doesn't have to be as difficult as it is often made out to be. If your idea and execution are good there's no reason you can't be successful.
Build Anticipation: If you want the launch of your site to be a success, you need to be able to build anticipation for it. Dropping a hint or two about the upcoming event you are planning can help get your target audience excited about what is coming soon and that will lay the ground work for the launch of your membership site. This will create enough hype for your launch to go well, and to get people interested even before they see your site. If you don't want to tell people everything about your site that's okay but at least tell them to get ready for an event on a specific date. This also means that it is not a good idea to launch your site without telling people anything about it beforehand. If you want people to actually look forward to your launch, feed into their innate curiosity by feeding them hints and clues. Launch on Time: No matter what, even if you haven't officially announced your "launch date" you should launch the site when you've said you would. This will force you to stick to your goal and actually work on it. Having the attitude that "It will be ready when it has to be" is crippling and will take you down. You have to live up to your responsibilities as a site launcher--you can't hide from that. Whether or not your site is as perfect as you'd like it to be by launch time is irrelevant; if the site is usable and presentable, you should launch it. It's okay if your visitors aren't blown away by their first visit to your site; what really matters is that you are professional and launch when you promise you will. There are no issues here because you're always free to update and upgrade your site after the launch.
Get Your Membership Site Content Plan Up and Running: Before you actually launch your membership site, you should have your content plan ready to go and it needs to be detailed. It's a good idea to create an editorial content outline and you do this by focusing on the minutiae so that the bigger picture is clearer. It's also good to have super high quality content ready for publication at least once a month. There are a lot of things to think about when you are in the early stages of a membership site launch so having your content ready to go ahead of time can only help. If you want to have an easier time making sure your launch runs smoothly, you'll need to have really great content ready to publish and a content plan in place for following. Always try to remember that the more you know about the competition and what they do, the easier it will be for you to create long term growth for yourself.