When they fill the plastic wrap, cut the stem off below the new roots, then plant the stem, moss and all. Now your leggy plant will have a shorter stem and will look rejeuvenated. The leafless lower stem can be left to sprout new shoots, or in the case of the dieffenbachia and some of the dracaena and cordyline species, the stem can be cut up and planted. New plants will eventually grow from each of the cuttings. You can air layer schefflera, dieffenbachia, ficus, and dracaena species that have lost their bottom leaves.
Good soil grows good plants.
You can buy packaged potting soil or mix your own using two parts garden soil, one part peat moss, and one part sand. Manmade substances like vermiculite are good substitutes for sand. The soil should ideally be moist, but not soggy. To properly store your soil mixture for future use, use a plastic bag or closed container to retain moisture. Some plant varieties require a specific soil mix which can be bought at your local nursery.