I help people to learn my language and no matter the age you can see the happiness when they manage to learn something new.
I started while at work, teaching a few words to my colleagues and then teaching my fiancé so he won't feel left out when we visit my family in Greece.
To communicate better and almost everyone I met they just love Greece summer.
It depends on the willingness and what you want to learn. If you want just to talk Greek it's much easier than to learn talk and write.
Usually the people I talk to they just want to be able to talk in Greek, to know how to greet people, introduce themselves or order in a restaurant.
Take a book any book you like and have read before in your language, in the greek translation and go page by page translating. At some point you will realise that you don't need the translation any more.