The document provides tips for quickly leveling up in the Restaurant City game. It recommends focusing on leveling up dishes to level 10 in each category by choosing dishes with ingredients that are easy to obtain. Serving level 10 dishes across categories would allow reaching level 20 in the game within 32 hours of play over a week, versus serving only level 1 dishes which would require over 85 hours of play daily. It also provides other optimization strategies like maintaining high employee energy, managing table and customer capacity, and leveraging social features to trade ingredients.