Whether or not you need to add fill depends on the style or look you want, the dynamic range of the camera or film stock, and what you are trying to balance the shadows against.
I try to keep things simple and not automatically add fill - not only does this makes things look natural, but it can make things go faster.
But if I need some fill, again, the technique varies by what is simpler to do -- maybe setting up a 12'x12' Ultra Bounce in the sun will be enough to fill in the shadows, or maybe just walking a bounce card with the actor, or draping some white cloth on the ground.
As far as exposure goes, again it depends on the look you want, but generally you do a little exposure splitting, not necessarily 50/50 though.
Again, it also depends on what the background is and how hot it is. If you are shooting digital, you have be setting the exposure to avoid clipping in the background and may have to compensate by adding more fill.