I recommend using the Apreuty High Frequency Machine ($30) close to your skin rather than on your skin for a more targeted, intense approach. If you leave a gap between the device and your skin, the current goes deeper into the skin. I prefer to cleanse my skin first, then use the high-frequency wand on dry skin for ten minutes in small, circular motions all over my face, and finish off my routine with my skincare products. With consistent use, my skin is less irritated and reactive, and the texture is much smoother than before. It definitely works as an effective spot treatment for active acne, including cystic acne, due to its antibacterial properties. It's one of those devices that will help you not overload your skin with actives.
Image Source: POPSUGAR Photography / Anvita Reddy