What’s the first step you would take to build a voltaic cell?

In a voltaic cell, current is produced by connecting an oxidation reaction half cell to a reduction reaction half cell in an electrolyte solution. Oxidation and reduction reactions (redox reactions) are chemical reactions involving a transfer of electrons from one atom in the reaction to another. When two different oxidation or reduction reactions are connected electrically by connecting the cathode to the anode, a current is formed. The direction depends on the type of reaction taking place at the terminal.

The first step would be to determine metals to be used as the cathode and the anode.