By situation
First time in Tsukiji
Arrive between 9 and 11. Bring cash. Do not plan lunch after 1 PM.
The streets are a few blocks between Tsukiji Station (Hibiya line) and Tsukijishijo Station (Oedo line). You will not get lost; you will run out of time. Most shops close by early afternoon.
Before 9 AM the shops are working for professional buyers. From 9 the market is open to everyone. Between 10 and 1 it is busiest.
Check the Today panel on the home page. If today is a market holiday or a Sunday, a good share of shops will be shut.