When working with the DOM in JavaScript, writing clean and efficient code is essential for both performance and maintainability. You should always minimize the number of times you access the DOM, since each access can be relatively slow compared to working with variables in memory. Instead of repeatedly querying the DOM for the same element, store references to elements in variables and reuse them. This makes your code faster and easier to read.

Another important practice is to avoid layout thrashing. Layout thrashing happens when you read layout properties (like offsetHeight or clientWidth) and then immediately make changes that force the browser to recalculate the layout, especially inside loops. To prevent this, group your DOM reads and writes: first read all the needed values, then perform all your updates.

Keeping your code organized is also crucial. Separate your logic into small functions, use meaningful variable names, and comment your code where necessary. This makes your scripts easier to maintain and less prone to errors as your projects grow.