I think I know what you mean by being fake - it feels wrong to be putting on a big false smile, maybe acting more friendly than you feel. But being polite and positive isn't being fake - it's showing your best self, and to make a good first impression this is all you have to do.
Don't try to memorise a lot of phrases or put on an act. A good first impression is about your general attitude. It starts before you even meet people: Whoever you are going to meet, do try to look good. That needn't be fake either - but try to be well presented, to take some care and to wear something appropriate. Don't ever keep people waiting - this is true in all situations unless there is a very good reason - and try to find out as much as you can about the people you'll be meeting beforehand. There's nothing sneaky about this; it's good manners and being interested in people.
When you do meet, a friendly smile and greeting, and showing interest in what people say is enough to make you look good. Ask a few questions, listen properly to the answers and you're already making a good impression. Good luck.