Should I study philosophy of science directly, or after understanding other branches of philosophy?

I wanted to learn philosophy of science and started with reading A historical introduction to the philosophy of science but found it surprisingly hard because a lot of concepts were unfamiliar to me. So I read a few books about Epistemology, and general philosophy, and used Plato encyclopedia of philosophy . However, now that six months passed, I made no progress: I couldn’t fully understand it when I read it second time.

The question is:

• Is it okay to study philosophy of science with no Philosophical background? if so, can you recommend an easy introductory book? if not, what are the branches that I should study before approaching Philosophy of science? Where should I start? (and please recommend me books for this as well).

Thank you for your feedback.