Methods and apparatus for evaluating a volume of an earth formation carried out using complex dielectric measurements. Methods include making measurements of complex permittivity at a plurality of frequencies; identifying an optimal frequency by: identifying candidate frequencies having a corresponding measurement with a respective sensitivity to at least one of i) salinity and ii) water-filled porosity, by determining that each respective sensitivity is substantially independent of rock texture; selecting a maximum of the candidate frequencies as the optimal frequency; using a table search method based on a forward model to generate an initial estimate of at least two parameters of the volume; and using the initial estimate as an initial condition for an inversion of other measurements at frequencies other than the optimal frequency to generate a final solution comprising final estimates for formation properties. The at least two parameters may comprise water salinity and water filled porosity.