It may be a bit old fashioned nowadays, but just go back to basics learn the 'Sunny 16' rule - that should suffice, especially if you shoot in RAW which will give you more latitude when processing the image.
Just start with:
Sunny Day, Distinct Shadows: Camera settings: F16, ISO 100, Shutter Speed 1/100th (or nearest reciprocal).
Slight overcast, Soft Shadows: . . . . . . . . . . . . . . F11, ISO 100, Shutter Speed 1/100th
Overcast, barely visible shadows: . . . . . . . . . . . . F8, ISO 100, Shutter Speed 1/100th
and so on
After that just adjust the various settings up and down a stop to maintain the right exposure (eg if you want a shutter speed of 1/200th then alter the ISO to 200 or change the F stop by one stop).
A bit of googling will come up with some tables to show various settings
http://easy-exposure.com/wp-content/uploads/2012/06/light-metering-012.jpg Sunny 16 rule - Wikipedia, the free encyclopedia