Start on the oldest blog posts. I just found them so useful. There’s a lot on how to keep your game manageable. The design document on the forum’s good too. Again, a lot of the tips are about keeping the game manageable so you’ll actually manage to get it finished.
I’d say aim for something like Choice of the Dragon, not something like Choice of Robots, for your first game. Linear’s good. I’d look at Heroes Rise too. It’s a rather linear, railroaded game, with a few significant branches, and hugely popular. I’d play them through, see how much choice you think you’re getting, then look at the code to see how much is actually there.