To start, ride a flat-bottomed sled down the hill, then coast along that path a few more times to pack down the snow. If you're feeling ambitious, you can also widen the track with a couple more runs. Once you have a decent trail, you can ice it up. If temperatures are below freezing, fill a spray bottle and spritz this track with liquid water. (If conditions are warmer than 32°F, then spray the track before you go home for the day, leaving it to cool down when temperatures drop overnight.) In particularly cold conditions, you can try dousing the path with a garden hose or buckets of water, but if you dump too much liquid at once, you run the risk of melting the snow. When the water freezes, you'll have an icy course that should allow your sled to slide down the hill at a much faster pace.