Dongqian Lake Scenic Area is very large. A day's bike ride on an electric scooter, going counter-clockwise, covers 32 kilometers.
Because the scenic area is so large, I think there are two main ways to experience it. The first is to take the subway from Ningbo city center to and from Dongqian Lake. You can either cycle the entire area or focus on specific spots. The second, and also recommended, option is to drive there, rent a car, or rent an electric scooter. I suggest finding a hotel near the lake, whether it's a budget chain or a four- or five-star hotel. Personally, I recommend staying at the Hilton Hotel, or looking for a lakeside café in Limin Village. These kinds of guesthouses cost between 400 and 600 yuan. Alternatively, you can stay at a Home Inn near the Dongqian Lake subway station for around 200 yuan.
The best way to experience Dongqian Lake is to explore several cafés, whether you want to spend money or simply enjoy a relaxing experience. You can leisurely sit there, enjoy delicious food, chat with friends, or simply daydream for an afternoon. Then, if you wish, watch the sunset or sunrise before going out for a bike ride, or simply take a taxi to Hanlin Old Street or climb the mountain to overlook Dongqian Lake (where your name is located). Overall, it's a fairly pleasant place to visit; there's no need to rush. It's more suitable for a genuine vacation than a special forces trip or a checklist-style tourist experience.