The video posted by Megan is a demonstration of gob smacking idiocy. For GA most CFIT accidents seem to start with a progression of VMC into marginal VMC into IMC. I teach my students that before you fly in poor weather you have to set hard limits. I recommend starting with 3 nm in flight visibility and 1000 ft AGL. Determining actual flight visibility is pretty easy with modern GPS moving map displays, if you can't see that geographic feature 3 miles in front of the little airplane on the moving map turn around. The same with altitude, if you can't maintain good VMC at your 1000 ft AGL minimum altitude then turn around.
I also tried to get all my students some exposure to actual marginal VFR conditions. There is a small airfield 11 miles from my home base. to get to it you have to pass over an inlet and up a bay. On several occasions I have had students get spatially disoriented in this short flight. Every student has remarked how difficult 700 and 2 actually was compared to how they thought it was going to be.