This paper first gives an overview of the multitude of chemical reactions taking place in aqueous solutions with multiple ligands and ions. Then, recommendations to avoid pitfalls in preparing such solutions in daily laboratory work are summarized. Thereafter, the theoretical aspects for calculating multiple ligand-ion solutions are described in detail. Information necessary to perform corrections of the absolute stability constants for the influences of pH, ionic strength, and temperature are given. The calculation of apparent reaction constants for ligand-ion interactions by using the corrected absolute stability constants and considering all possible reactions between a ligand and an ion in an aqueous solution will be introduced. Thereafter, by employing the apparent reaction constants and an iterative method, the determination of multiple ligand-ion equilibria to find the desired ligand or ion concentrations are presented. Thus, this paper can be used as a guide to the principles of programs calculating multiple ligand-ion solutions, to choosing the appropriate program for one's special requirements, and to preparing multiple ligand-ion solutions properly.