The first step is to identify the greatest common factor. In this case it looks like we can factor a 3 and an x^3
Now we just do the factoring.
3x^3 ( 2x ^ 4 + x - 3 )
Don’t forget to also identify any numbers in the greatest common factor as well. That can often greatly simplify the problem for later work (when we have later work for the problem anyway....).