Hello there
1) First step would be introducing a game at local store or your gaming group or group or friends etc. It depends on a local store but most of the time, they are glad that someone is creating programm for them. Some of them will promote you, some of them will gave you a small table at the basement. It depends
2) If you are doing introduction outside your group that you know and they know you, try to look representative. You will be suprised how a great number of demoers are doing introductions for their games half sleeping, in non-clean clothes with an odour of Garlic from their mouth
3) Know your game. You should probably know most of the interactions that could happen in a game. Also, if you are from Arena, be sure to check how Melee +X and Pest trait works in Academy. This way, your demoing will be fluent, you will act as a judge and had proper respect while deciding issues.
4) Never ever start introduction in a manner - Do you know game XYZ? Well, this game is better. Sometimes, those ppl love the game XYZ very much and sometimes it is an only game they know (i am looking at you MtG).
5) Settings - i have a small package of 12 cards on which i explain very briefly how academy works. If they get interested, i will distribute prepared spellbooks and explain each card in those spellbooks. That is the most "boring" part as players didnt play but study. But if they liked my brief explanation, most of the times they were able to get over this learning step.
6) Guiding - it happens, that player which is unsure just pass you his spell book and ask, what to play or will ask for permission to play specific card. Dont do that. Ask him what HE wants or what he expects. Sometimes, you gave "defensive" spellbook to an "agressive" player. Here is the part you should explain that each mage can have different spellbook thus approach.
7) Have Fun. If you are not having fun, guys at your table doesnt having it too
Hope it helped.