One toolbox, many tools
Most of the geologic problems that I investigate are related to either petrology, tectonics, or volcanology (sometimes all three at once).
I use a “one toolbox, many tools” approach to these problems. My most frequently used ‘tools’ are fieldwork, geochemistry (bulk and mineral chem.), paleomagnetism, and thermodynamic modeling. Occasionally I reach farther into the toolbox and pull out tools like geochronology, thermochronology, sequence stratigraphy, paleontology, etc. – whatever is needed.