I do not know Sanskrit and to be honest, my Greek is shaky at best. I rely on the wisdom and translations of others who spend their whole careers teasing out subtle shades of meaning.
For this journey through the Bhagavad Gita, I’ll mainly be using Eknath Easwaran’s translation (Easwaran, Eknath. The Bhagavad Gita. Nilgiri Press, 2007). It is readable and his commentary is helpful. Occasionally I compare it to Georg Feuerstein’s translation (Feuerstein, Goerg. The Bhagavad-Gita: A New Translation. Shambhala, 2014).
If you’re interested, you can compare the publicly-available 1900 translation by Sir Edwin Arnold.
As for the Bible, I typically use the Common English Bible (CEB) for devotional purposes. and the New Revised Standard Version (NRSV) for more scholarly purposes. I’ll make a note if I use a different translation. I’m especially fond of the way the CEB translates “Son of Man” as “The Human One.”