To identify an unknown salt you test for its positive ions (cations) and its negative ions (anions) separately, then combine the results. No single test is enough on its own.
For the metal ion, start with a flame test: dip a clean wire loop in the solid and hold it in a blue Bunsen flame; potassium compounds give a lilac flame, for example. Then dissolve some of the salt in distilled water and add sodium hydroxide solution, noting the colour of any precipitate and whether it dissolves in excess. Warm a fresh sample with sodium hydroxide and hold damp red litmus paper at the mouth of the tube to check for ammonia, which shows ammonium ions.
For the negative ion, add dilute acid to a fresh sample: fizzing that turns limewater cloudy shows carbonate. Add dilute hydrochloric acid then barium chloride solution: a white precipitate shows sulfate. Add dilute nitric acid then silver nitrate solution: a white precipitate shows chloride, a cream one bromide and a yellow one iodide. The acid is added first to remove carbonate, which would give a false precipitate.
Record every result in a table. Example: a blue-green flame, a light blue precipitate with sodium hydroxide and a white precipitate with barium chloride means the salt is copper sulfate.