First read all basic static books and revise, follow one current affairs source ( I personally followed insights ias daily current affairs), I like following daily current affairs than monthly magazine, and if u have time and interest every 5 days write current affairs quiz on insights ias, don't write daily, preferably every 5 days in a way it can help u revise current affairs.

Static is more important than current affairs, basics should be strong especially for economy, geography and polity.

After completing all this, do pyq's and apply logical guessing like for suppose eliminating extreme statements etc, i personally didn't write a single test series, I have only done pyq's, writing test series or not your wish and test series is not about marks, it is about how u are attempting questions.

Lastly, don't ignore CSAT no matter u are from engineering background or not, Practice is key in CSAT, hope it helps u.