Having used both the meguiars and the 3m kit on my Audi the 3m kit is far superior and lasts a lot longer, you can then buy and apply a clear uv lacquer to stop them yellowing over time.
Process is dead simple you use a household drill with the kit to gently sand the cloudy yellow old uv protector off the lights, then buff them and as mentioned above you can then apply a clear uv coating back on if you wish.
3M Headlight Lens Restoration Kit | eBay