$\displaystyle (x - y)^2 - 4(x - y) + 3$

I need some help with these kinds of binomials. I can never seem to get it right. I tried:

$\displaystyle (x - y)^2 - 4(x - y) + 3$

$\displaystyle [(x - y)^2 - 4(x - y)] + 3

=(x - y) [(x - y) - 4] - 3$

After that I don't know what to do, or I could have done it wrong already. Could anyone help please?