2x^3y^3-x^2y^3+2x-y

factor by grouping

notice the coefficients are all 2 or 1. So, I'd try

2x^3y^3-x^2y^3 + 2x-y
x^2y^3 (2x-1) + 2x-y
(x^2y^3+1)(2x-y)