If you haven't yet, you should check out the latest thing on FileBall, the first level of an upcoming scenario called "C.H.E.F.". The author, Andreas, emailed me asking for advice with his "almost completed" scenario, and offering to help with Eternal. I recommended he release something less than a whole scenario first, since he's not released anything before, hence his release of this first level.
In my opinion he's already better than I am, so I can't really offer him any constructive criticism, but I know there are people here way better than that too, Don and Goran and Simon and all, who might be able to give him some pointers. Aside from helping a talented new mapmaker, you'd be helping me too, since he's also going to be working on Eternal in between work on his own project.