Hey /sci/

Sorry if you get this question often;

I'm trying to get better at maths; I want to be able to intuitively follow along and sort out problems, and be able to design things using primitive math elements.

I know the answer is to really just practise and hone my skill of maths. but practise what? is there some good quality textbook that you would recommend? or some sort of course structure that I can use to piece things together myself?

My interests are in computer science / engineering type fields, and I've finished my bachelor and realised that I don't know shit and this work is easy monkey shit, and wish I took maths instead.

I'm reading a book now about Richard Hamming, (Hamming codes, etc) and it's a nice read, but when it comes to the maths, I look at it with a bit of a yearning to think that he had this sort of power to scribble notes and "design" ideas with; the only thing I can "design" with is python code.

( probably places would be refresher in calc, geometry, graphs, and whatever "set theory" comes into being? )

How can I get good at maths? is there an index of mathematic concepts that I can progress through?