First, keep it clean. Use soapy water and a cloth to wipe down the frame, especially around the joints and where the hands grip the metal. Make sure to dry thoroughly to prevent rust. Check the wheels to see if dirt or other debris has accumulated and remove any with a small brush. Test the wheels by spinning them; they should roll smoothly. If they don't, use a lubricant or silicone-based spray to get them whirling again.