I agree with Bob, take a class first and foremost. Something you are going to learn working with Vans' kits is that they will show you one way, but a lot of the time the community has best practices that are far better than what they show you. The instructional information from Vans' even acknowledges that they are just showing you one way. Taking a class will expose you to many of these kinds of things.
As for specific classes, the EAA SportAir Workshops can be good, I haven't taken their sheet metal class, but I did take a fiberglass class with them. The one thing I will say about that is that the main project of the class showed us a technique that was definitely not according to the instructions from Vans, and while it works, I'm not sure I'm 100% sold on it. I would have liked to know ahead of time that they were explicitly not showing us the recommended technique by Vans. Maybe their technique is better, maybe it isn't, but I don't know. Personally, I attended the Fundamentals class for sheet metal at Synergy Air South. They did a decent job, but I also have some complaints. The class felt very rushed to me, like it really needed to be two days. They had a senior person overseeing a trainee who taught the class the day I showed up, and it was a bit frustrating that the guy clearly didn't know the material he was teaching as well as his senior, but he didn't seem willing to just say he didn't know the answer. So he'd sit there and try really hard to come up with an answer rather than just ask the guy standing right there who obviously knows. The Synergy Air class also felt like they were trying to sell you on their builder assist program really hard, like the Fundamentals was more about getting you in the door so they could make a bigger sale than anything else. It's probably a perfectly good program, but I didn't want it and there was a lot of attention given to it all day. That said, the senior tech who was overseeing is incredibly knowledgeable there and absolutely knows his shit. I get the impression he is a bit overloaded. At the end of the day, I learned soooooooooo much in both the SportAir fiberglass and the Synergy Fundamentals sheet metal classes, that they were overwhelmingly worth the time and money. TL;DR- Take a class, its worth it. AFAIK the SportAir sheet metal class has you build RV TRAINING PROJECT-1, that's what it looked like from across the room. Synergy Air definitely has you build RV TRAINING PROJECT-1 in their class.
After you take a relevant class, then you should start building training kit(s) until you are satisfied that had those been real airplane parts, you would gladly fly in the airplane they become a part of. It's okay to build more than one training kit, and a lot of people do. You are going to make a lot of mistakes even after taking a class, some of which might make you want to try again, and its okay. That's what the kits are for. Maybe other people are wizards at this, but I'm working on my third RV TRAINING PROJECT-1 (one in class, one in my hangar, made a couple mistakes, working on a third one, going for perfection, also doing internal priming this time).
As for which project, I'd suggest you not limit yourself to just one. The blind rivets project is newer AFAIK, and is probably directed at RV-12 builders. RV TRAINING PROJECT-1 is just a good kit that engages a lot of interesting problems, and I definitely recommend it. Can't speak for the toolbox nor the light.
(and expensive 
). My understanding is fancy bucking bars are not essential for RV-12 given it's mostly pulled rivets. Is that correct?
