I recommend A Primer of Biblical Greek by Croy,as it has a very good pace and comes with resources for self-study (online practice, quizzes, etc.). We use this for our students in senior year who are interested in learning Koine and generally have a Latin background. Koine, specifically biblical, will be best learned by reading the bible, which this text does well.

Others have recommended Mounce for biblical studies, though I have not worked through this text.

If you are interested in learning all dialects of ancient Greek, I strongly recommend working through Luschnig (better condensed form of Hansen and Quinn), reading the JACT Reading Greek and then Attica for intermediate.