Stoic Resources

I’d recommend starting with:
Sellars, J. (2020). Lessons in Stoicism: What Ancient Philosophers Teach Us About How to Live. Penguin

If you still want more then I’d get:

Sellars, J. (2006). Stoicism. University of California Press.
This is the book we use for the Stoic Essential Studies (SES) program at the College of Stoic Philosophers.

Then enroll:
Stoic Essential Studies (SES)
https://collegeofstoicphilosophers.org/ses/

Only then, read the Roman Stoics

Really, only after you’ve read the above! You’ll get so much more from the Romans.

For Marcus Aurelius, I recommend:
Marcus Aurelius. (2011). Meditations: With Selected Correspondence (R. Hard, Trans.). Oxford University Press.
or
Marcus Aurelius. (2021). Meditations: The Annotated Edition (R. Waterfield, Trans.). Basic Books.

For Epictetus:
Epictetus. (2014). Discourses, Fragments, Handbook (R. Hard, Trans.). Oxford University Press.
or
Epictetus. (2022). The Complete Works: Handbook, Discourses, and Fragments (R. Waterfield, Trans.). University of Chicago Press.

For Seneca’s letters, I would go with:
Seneca. (2015). Letters on Ethics: To Lucilius (M. Graver & A. A. Long, Trans.). University of Chicago Press.
Although I also really like the old Richard Mott Gummere translation published by Dover.

If you want to keep going...

The next obvious step would be the Marcus Aurelius Program (MAP) at the College of Stoic Philosophers:
https://collegeofstoicphilosophers.org/map/

There, you’ll have to buy some books that are appropriate for continuing your journey.
By the end of the program, you’ll be equipped to walk alone.

And from there, you’ll find what you need based on your own interests.

My Treasures

If you are curious, these are some of the books I love and treat like treasures.
I come back to them often and consider them my babies.

Roman Stoics

Epictetus. (2014). Discourses, Fragments, Handbook (R. Hard, Trans.). Oxford University Press.
Marcus Aurelius. (2011). Meditations: With Selected Correspondence (R. Hard, Trans.). Oxford University Press.
Marcus Aurelius. (2021). Meditations: The Annotated Edition (R. Waterfield, Trans.). Basic Books.
Seneca, L. A. (2015). Letters on Ethics: To Lucilius (M. Graver & A. A. Long, Trans.). University of Chicago Press.

Books I love about Stoicism

Sellars, J. (2006). Stoicism. University of California Press.
Buzaré, E. (2011). Stoic Spiritual Exercises. Lulu.
Long, A. A. (2002). Epictetus: A Stoic and Socratic Guide to Life. Oxford University Press.
Sellars, J. (2020). Marcus Aurelius. Routledge.
Sellars, J. (2003). The Art of Living: The Stoics on the Nature and Function of Philosophy. Ashgate.
Hadot, P. (1995). Philosophy as a Way of Life: Spiritual Exercises from Socrates to Foucault. Blackwell.
Hadot, P. (1998). The Inner Citadel: The Meditations of Marcus Aurelius. Harvard University Press.

Down the rabbit hole

Rist, J. M. (Ed.). (1978). The Stoics. University of California Press.
Gould, J. B. (1970). The Philosophy of Chrysippus. State University of New York Press.
Graver, M. (2007). Stoicism and Emotion. University of Chicago Press.
Hahm, D. E. (1977). The Origins of Stoic Cosmology. Ohio State University Press.
Jedan, C. (2009). Stoic Virtues: Chrysippus and the Religious Character of Stoic Ethics. Continuum.
Sambursky, S. (1959). Physics of the Stoics. Princeton University Press.
Thom, J. C. (2005). Cleanthes’ Hymn to Zeus: Text, Translation, and Commentary. Mohr Siebeck.
Edelstein, L. (1966). The Meaning of Stoicism. Harvard University Press.