League of Legends (LoL) Question: how to teach league to new players

I feel like a good starting point would be to let your friend pick a role and a champion. There's 5 roles and around 158 champions as of now so if you can minimize it a bit, that'd be a good start.

Once that's covered, you could always teach things about how to play said role, things to think about and how to execute certain topics (think about say roaming to other lanes when it comes to midlane and so forth). Could also be champion specific things if you know about the champ in question. Talking a bit about matchups for the champion could also work out.

Also, you should lay out to your friend what our macro goals are, like turrets and dragons, because the game has been working around them the most lately what with Dragon Souls and Ancients. They will need to keep an eye out for dragon spawn timings as much as for last hitting minions.