Reddit reviews Learn New Testament Greek

Visual Greek. Learn using cartoons!!!! A similar method is Greek To Me. Again, learn using cartoons! I've read most of the book and it was a HUGE help. Also, both are Koine, and the visual greek method uses Mounce's book, which is THE standard intro. Mounce also wrote an easier intro for people who just want to know enough to do basic bible studies and use some of the better Greek tools out there, it's called Greek for the rest of us. Other books that take it easy on you are Learn Biblical Greek by John Dobson and English Grammar to Ace New Testament Greek. If you're wondering "Why grammar?" it is because you need to know how grammar works. If you know how it works in your language, you'll have a better grasp of grammar in other languages (at least you'll know what the books you read mean when they talk about active and passive verbs etc...).

Not free, but not expensive either: all the Greek I know comes from John Dobson's Learn New Testament Greek, which is a pretty good introductory text. The accompanying CD is pretty good too for practicing pronunciation.