Queries About Specificity

So I came to this topic specificity. I learned it a year ago. But I forgot because I took it lightly But this time around, after having seen many resources I realized it’s one of the most important things to consider. Now this is what I know, and I would like to know if there is something I am missing out on.

This is how specificity is calculated:

1) instyle weight 1000, id 100, class 10, rest other selectors 1 (Learned from CodeAcademy)

2) If 2 elements have same specificity, then the latter one wins

3) Usually, specificity with higher rate is considered by the browsers.

These are the stuffs that I understood. Is there anything else to know or consider?

Could you please tell me how to go about with specificity when I design the style sheets with different stuffs in it? Like in Login pages, normal profile pages, etc, etc in WordPress?

Cheers ??