Do I need to make reservations?

For high-end sushi or omakase, yes—sometimes weeks in advance. For izakayas and ramen shops, it is usually first-come, first-served.

Is it rude to eat while walking?

Generally, yes. It is considered polite to stand near the stall where you bought the food, finish it, discard your trash there, and then move on.

How to plan your own food tour of Tokyo

Focus on one neighborhood per day to maximize eating time and minimize transit. Use the Tabelog app to filter by rating (3.5 is excellent) rather than relying on Google Maps reviews, which are often tourist-inflated.

Map your cravings by station. Don't jump across the city. Pick a hub like Shinjuku, Ebisu, or Tsukiji. Group your stops within a 15-minute walking radius of the station.
Use Tabelog for research. Download the Tabelog app. In Japan, a 3.0 rating is average, 3.5 is great, and 4.0 is world-class. If a place has a 3.55 or higher, book or line up early.
Schedule 'stomach breaks'. Plan for 3 main meals and 2 snack stops. Tokyo portions are smaller than in the US, but the richness of the food adds up. Walk at least 10,000 steps between meals to stay hungry.
Master the queue culture. If you see a line of locals, join it. If you see a line of tourists, keep walking. Carry 5,000 yen in small coins and 1,000 yen notes; many small shops do not accept cards.

Do I need to make reservations?: For high-end sushi or omakase, yes—sometimes weeks in advance. For izakayas and ramen shops, it is usually first-come, first-served.
Is it rude to eat while walking?: Generally, yes. It is considered polite to stand near the stall where you bought the food, finish it, discard your trash there, and then move on.