It's hard to make a sticky for a game like this since it's constantly changing. The only stickies that have really been tried so far have been denied on the grounds that stickies can't just be a post full of links to somewhere else.
Which is honestly the best way, rather than trying to explain everything.
I suppose we could make a "New to LoL? Check here first for the Basics!" topic where we recommend several 450 champs of differing playstyles, the correct way to actually practice when you first begin, important things such as CSing and that. Then a slightly "advanced" section with jungle timers and tips on map awareness and that sort of thing.