Students ask me all the time: Now that I've had a year of Greek, where should I begin as I translate the Greek New Testament?
That's a great question!
Not all New Testament Greek has the same level of difficulty!
I always begin with 1 John.
The book is short, has repetitive vocabulary, and contains a simple sentence structure.
Next?
The Gospel According to Mark.
It's storytelling at its best -- brief sentences, occasional Semitic influence, clear narrative.
I've taught second year Greek students Mark about a dozen times in my 50-year teaching career.
What fun!
After that, I'd recommend either Philippians (4 simple chapters) or 1 Thessalonians (5 easy chapters).
Keep this up and one day you'll be reading Hebrews -- very sophisticated and rhetorical Greek with long, nested sentences and an elaborate argument!