None of us like to carry lots of gear, so if you don’t have a light meter handy, fear not! It’s likely you can use your camera’s auto mode to gather a basic idea of the settings you need for a decent exposure. Take a shot in auto mode, and hit info to gather the shutter speed, ISO and aperture settings. Copy the settings into manual mode, and using the light metering indication (usually looks like the diagram below):
You can then shift individual elements like shutter speed, sensitivity, aperture etc. to get the aesthetic results you are after – negative on the exposure scale will yield darker moodier images, and positive on the scale will create brighter, lighter images.
Once you get a feel for your camera settings, and practice enough, you’ll start to be able to ‘read’ the light in your scene and will come to know which settings work for which types of end results.