IUI Success

I am about to begin my first cycle of IUI with Chlomid and donor sperm. I really want to do anything I can to make my IUI successful. I've read that Chlomid makes your cervical mucus thick and can hinder implantation so you can take cough syrup like Robitussin for a few days before insemination and it will thin out your cervical mucus, thus increasing your chances of pregnancy.
Has anyone else heard of this of know if this works?