Make sure you have robot-instructions in your to-do list. In the rush of the day you'll escape items that require decisions. Using verbs is a simple way to test it.
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As much as it may seem handy to keep many windows open in your screen, ready to work with, they are more likely to become a focus trap. Instead, have a super easy super quick way to open whatever you want in a blink and keep fewer windows and tabs open.
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Use at least a part of your day to Deep-Focus activites. Allow yourself to disconnect from everything(!) for a period of time and dive into some high-value complex tasks.
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If you want to optimize your focus at any moment, take a piece of paper and write down what you're thinking of - specially, what are you worriyng about?
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Work in time slots of high focus. Bundle small things on a list to avoid focus-shift. Like traffic lights, things get better if they have a kind of rhythm.
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Turn off e-mail alerts, or at least close your e-mail application when you need focus. Be sure there are no bottom screen messages or flags of any kind.
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