Well, those were only suggestions, but when is the raffle happening?
Having been on internet forums since I was just 10 years old (now 23), I've seen lots of bad/unfair stuff happen. While I'm in no way implying the intentions of any "newbies" here (I'm still new myself), there are often times where people will only join a forum for the sake of a contest or what-have-you and then never show their face around the forum again once they win or lose. Makes it slightly unfair to the people who have dedicated months or years to said forums. Not to mention people making multiple accounts and winning that way.
That's why I like the idea of having a slight requirement before joining. Depending on when the raffle is supposed to start, anyone who truly just joined this forum for the sake of betta fish ownership and to be a part of the community should be able to stick around and make a certain number of posts before the raffle starts? I feel like anyone who is just here for the contest won't want to waste their time or they'll just forget, therefore, never entering.
Of course, I could just be overthinking here and making things over complicated xD!!!
IP address thing could work, but a mod/admin might have to get involved to do that.