Start by matching the environment, conductor count, and insulation material to your installation. For indoor lighting or general power runs, twin with earth cables with PVC insulation are common, with 1.5 mm or 2.5 mm cross sections from brands like mat-star; if the run may bend or flex, look for a tear resistant cable advertised as resistant to bending fatigue. Decide whether you need a shielded design or a simple twin plus earth based on interference and protection needs, and pick the jacket material (PVC or ABS) accordingly. Finally, confirm compatibility with your fittings and whether the cable is rated for indoor use.