The one must-do
Top of the board, large: the single task that defines a successful day. If you complete nothing else, this one thing. Write it as a finished state: 'Bug fix shipped and deployed,' not 'Work on the bug.' If you can't name it in fifteen seconds, spend two minutes deciding before writing.
Time blocks
A timeline from your start time to your end time, divided into one to two hour blocks. Write what work mode goes in each block, deep work, meetings, email, errands. Don't schedule to the minute. Block the type of work, not every individual task.
The three tasks
Below the must-do: two or three concrete tasks in order of priority. These are the next tier, important but not the day-defining item. Each task should be completable in 30 to 90 minutes.
Scheduled commitments
A column on the right: meetings, calls, and hard deadlines. When are they and how long are they? This section prevents the rest of the day from being planned without accounting for the non-negotiable time constraints.
Notes and scratch
A box in the corner, a free zone for things that come up mid-day. Phone number someone texts you, a quick idea, a reminder to follow up. Having the scratch space on the board means you don't need to switch tools when something arrives.