advises for realistic lighting...

i would like to have advises for lighting a scene in the most realistic way. what parameters ( and what values…) do i have to change ?
if i want to create a ambient light in my scene, like the sun light, can i use only
glLightModelfv(GL_LIGHT_MODEL_AMBIENT, model_ambient);
or is there others parameters to change to improve realism ?

All your knowledge is welcome…