Amsterdam has an extensive public transportation network of buses, trains, and trams which are convenient, reliable, and cost-effective. However, if you plan on exploring the city primarily on foot, walking and biking are great options, with numerous bike rental shops at your service. Some costs to consider are the 1-hour public transport pass (3.20 Euros) and bike rentals (around 15-20 Euros per day).
If you have more time, you can consider a day trip to Keukenhof Gardens to see the famous spring tulip blooms, or explore the city's street art scene by visiting the NDSM Docklands. If you have less time than four days, you can exclude the Zaanse Schans trip, or pick other attractions that interest you the most. You can also take advantage of the numerous food, cultural, and nightlife tours available to make the most out of your time in the city.