Stirring- example- if you want to make NaCl solution, you mix water and NaCl and if you stir it the dissolving will be fasten up.
Heating- As we all know, on heating expansion occurs. In expansion molecules of any state of matter on gaining energy start moving away from other molecules, thus, having more intermolecular space and in this condition, if we add some thing that can dissolve in the substance it can hold more than when it was not heated.
Crushing- if the size of the solute is less, then it can be easily mixed up or dissolved with the solvent.