Need help with A-level Mathematics.

I am currently in Year 13 and have been doing quite well in Core 3 so far. I've been getting A*s and As in all of the 'end of chapter assessments'.
However, I keep consistently getting 54/75 in the Solomon papers that I'm doing for practice. I have decided to start with Solomon papers because hopefully then the original past papers will be nicer in comparison.
The papers I intend to do are Solomon, Elmwood, Edexcel and Edexcel IAL.

How do some of you people get to the point where you're consistently getting 90+ UMS?
Should I start doing lots of papers (i.e about 2 or 3 per week now) and learn from the mistakes I make in them, or spend time doing questions specifically for each topic before doing past papers (i.e. Solomon worksheets)?
I got an A for AS, but I'll be re-sitting C1 this summer because my UMS in that was just below an A and ideally, I want at least 90 haha.

How many Solomon papers have you done?

Are you constantly losing marks on the same topics? If so, you don't fully understand that topic, review it again.