If the intermolecular forces between molecules of a substance

If the intermolecular forces between molecules of a substance were very small what effect would you expect this to have on the boiling point and vapor pressure of the substance? What properties would you look for in a molecule in order to have a low boiling point and high vapor pressure? Should the atoms of the molecules be large or small? Why might this matter? Give two or three examples of molecules where you might expect the intermolecular forces to be very small.