I've bought books from Amazon and use anything I can get free online as well as the free version of Duolingo (there's an iPhone App). The hardest part is the alphabet - I'm great if everything is upper case but rubbish still with lower case letters!
Read and Speak Greek for Beginners with Audio CD, 2nd Edition (Read & Speak for Beginners)
https://www.amazon.co.uk/gp/product/...?ie=UTF8&psc=1
Greek Script Hacking: The optimal pathway to learn the Greek alphabet (Teach Yourself)
https://www.amazon.co.uk/gp/product/...?ie=UTF8&psc=1
Go for it! 10 mins a day is better than nothing at all. Good luck!
Oh, and I read somewhere recently that the most popular language learned on Duolingo is Welsh! Mrs CN uses it and loves it.