Kanazawa is compact and most of the main sights are walkable from each other. The Kenroku-en and castle district, the 21st Century Museum, the Nagamachi samurai district, and the central market are all within 20 minutes' walk of each other.
Two loop bus lines cover the main tourist areas: the Kenroku-en loop (right-circuit) and the Higashi Chaya loop (left-circuit). A one-day bus pass (about ¥500) is worth buying if you plan to use the buses more than twice.
Kanazawa Station is about 2km from the central sightseeing area, so it makes sense to take a bus or taxi from the station and then walk between the sights. Taxis are plentiful. The city has a bikeshare scheme (Machi-nori) with stations near the main sights, which is a good option in good weather.