I'm dividing polynomials, operations like: $\displaystyle a^{2}-b^{2}+2bc-c^{2}\div a+b-c$

I know that I can organize first the polynomial in decreasing order for one letter by taking the biggest exponent of that letter and reorganizing form biggest exponent for that letter to lowest. But how can I do with the polynomial I just wrote? What's the criteria? For example for this case, I can organize decreasingly for the variable $\displaystyle b$, and I get up to this point in the reorganizing process: $\displaystyle -b^{2}+2bc$... but now the exponent for $\displaystyle b$ is zero for both the terms, $\displaystyle a^{2}$ and $\displaystyle -c^{2}$

Which one should be put first in these situations?