This article is to give a brief introduction on how to utilize wavefunction-based multireference methods to predict electronic structures, spectroscopic properties, and reactivities of transition metal complexes. To this end, we choose a series of high-valent iron complexes as examples. Specifically, we first focus on how to choose an appropriate active space, then delineate how to extract electronic-structure information from highly correlated multireference wavefunctions and, finally, elaborate how to establish the correlation of electronic structures with spectroscopic parameters and reactivities.