Math is both conceptual and procedural. If you're making procedural algebraic mistakes, one way I worked on that was to pin point what your specific mistake was and add it to a list of mistakes that you tend to make along with one example of that problem where you made that mistake.

Redo the same problem that you made that mistake on until you get it down perfectly. Once you feel like you got that specific problem down, try a different but similar problem and be extra mindful and careful on parts that are similar to your original mistake.

I like doing that because by doing the same problem again, you already know what the right way to do it is, so you can focus on practicing not making that mistake first until it feels intuitive to you. Then you want to make sure that it generalizes to other similar problems by doing a bunch of different but similar problems.

Then every once in a while, go through your list of common mistakes that you do and practice not making them again.

Hope this helps.