I am not a member myself (keep putting it off yet I don't know why...) but I do have friends who are.
When a concert is announced, FC balloting only applies to people who are Members by the time the ballots go out. Joining now would NOT allow you to ballot in this round.
Ballots have already gone out and the deadline in June 30th.
So while it would be fantastic to join the FC, I would not recommend doing so simply because you think you're going to get tickets.
Also, being a FC member does NOT automatically mean you're guaranteed tickets. I know people who've been members for years and have only hit once or twice. There are others who get multiple hits. It's a lottery and a lot is left up to chance.
If you are not a current FC member and still wish to get tickets, there are usually fans (and scalpers) selling them through Yahoo!Japan auctions. But, be prepared to pay a pretty penny for those.
If you have any other questions about the balloting, tickets, the concerts, going to Japan in general for the concert (to try and get tickets at some point there through scalpers), please go ahead and ask here. I will try to answer or find the answer.
I know tutorials have been posted before, so google is always your friend. :)
EDIT: It came up in the comments that to use Yahoo!Japan, you have to have a subscription to their service to bid over 5000yen, which .....is required for concert tickets because there won't be any under that. Rinkya is a fairly good bidding service for Yahoo!Japan, but they do charge a fee. Most sellers will not ship internationally, as well, so if you go on your own to register through Yahoo!Japan, be prepared to not be able to receive tickets.
There are ways to contact the hotel you are staying at if it's close enough to time and and you already have your reservations and have them receive your tickets. But that is a completely case by case thing. :)
Hopefully we can all discuss and figure out the best ways to get tickets this year. :)
karadin reminded me about I-TM4U. This is a great service for ALL Japanese auctions, goods, etc, not just tickets! Their fees are fairly low and the shipping is super reliable. Once the tickets are released, make sure you check it out!