Please follow this procedure for solids.
Note down the MW of the compound and the volume required for the experiments.
Calculate the weight needed for making the solution and weigh it accurately.
Dissolve the material in smaller quantity of water.
This is done to avoid exothermic/endothermic dissolution in the volumetric flask.
Then, quantitatively transfer to the volumetric flask with wash cycles.
Makeup the solution to the mark, close the volumetric flask and mix gently.
Store at appropriate conditions for further use.