Edit your User page and insert one or more of the following bolded strings (including the four curly braces), preview your edit, and when it looks right, save it.
To see a visual display of the below templates check out the Tip of the Day Display template gallery.
{{totd}} – the main userspace version of the tip of the day template, with border, centered in the middle of the page. Complete with inspirational light bulb. Border color can be custom modified.
{{totd b}} – a more compact version of the above template. Useful for columns.
{{totd3}} – a purple box version, useful for displaying the tip in columns.
{{totd-random}} – this is the tip of the moment template, which automatically displays a different tip every time you enter a page it is on. If it doesn't update, try clearing your browser cache.
{{totd-tomorrow}} – this shows tomorrow's tip, and is used by Wikipedia tipsters to make sure that the tips are up-to-date and corrected before they go live.
{{tip of the day}} – the borderless version, with light bulb.
{{totd2}} – the borderless version used on Wikipedia's Help page (which already has its own borders). (No light bulb).
{{totd CP}} – like the help page version, but with a box and light bulb. Spans the whole field (screen or column) that it is in.
{{totd-static}} – like the totd version but the date is static. You have to manually change the date. Good for testing purposes.
To have the current day's tip and tomorrow's tip show up at the bottom of your talk page, below the last message, paste this code anywhere on your talk page (preferably at the top):