Gonna delete my id soon......please help (27tard here)

As a 27tard which test series should I purchase?
I'm a dummy school student studying from online batch.
I'll be doing my 12th from pw lakshya batch.
So which offline test series should I buy? I want to give as many tests as possible so that I don't make many silly mistakes (as i do now)
So I was thinking of a test series that starts from july or smthg and one that starts from nov or dec ig.
Please tell me which one should I buy......which is relevant and reccomended? Where should I solve questions from subject wise?

And also seniors do lemme know your most imp tip🙏