I approach available light photography with a color meter and a full set of CC filters. I match the color output from a small strobe unit to the color temperature of the ambient light, then "program" a gentle fill ratio. The results are much more than you might expect from an available light approach.
35mm Ektachrome
24mm Lens
1 2 3 4 5 6 7
Fill flash effective,
yet unobtrusive.
Available Lt.