Most salts will break down into it's ions when added to water, but I have to assume that you mean how to get it to react further. (as in affect the equilibrium) The only thing you can do is change the temperature. If you want more of it to dissolve, then you usually need to increase the temperature, but it depends on which side of the reaction is endothermic.
Edit: Changed to most salts, as not all salts are soluble.