You don’t need a light meter.
You can set the exposure using the Sunny 16 Rule.
In bright sunlight, set the lens opening to f/16 and the shutter speed to the reciprocal of the ISO.
You're photographing in bright sunlight.
What's bright sunlight?
Use the shadows to evaluate the brightness of the sun and sky.
In bright sunlight, shadows are dark with sharp edges.
Let's say you've set the ISO to 200.
For the correct exposure, set the lens opening to f/16 and shutter speed to 180.
1/180th is the closest shutter speed to ISO 200.
In other lighting situations, use the table below.
Lens opening: f/16
|Dark with sharp edges|
|Slightly overcast||Add 1 stop to f/16: f/11||Bright with fuzzy edges|
Add 2 stops to f/16: f/8
Add 3 stops to f/16: f/5.6
Add 4 stops to f/16: f/4
Add 1 stop to f/16: f/11
For more a more complex method to determine exposure, see Light & Exposure Values.