How does one improve the setting of grout (or other cement-based products)?

To mix grout, you'll need an empty bucket, a container of water, a sponge, and a trowel. Adding a polymer grout additive to your grout (if it doesn't already include one) will increase your grout's durability. Before using mixed grout, let it "slake" for 5-10 minutes so it strengthens.