1. Pipe trick: Many article titles are disambiguated with parenthetic qualifiers, like this: [[Self (psychology)]]. But when you want to include such a link in the body of an article, this would look rather awkward. So all you have to do is use the "pipe trick", like this: [[Self (psychology)|]]. Notice the "|" character stuck in there at the end of the link? That makes the link look like this: Self, without having to type the name of the link after the pipe! This trick also works with namespaces, so that [[Wikipedia:Tip of the day|]] (again notice the pipe character) displays like this: Tip of the day.
2. Plural trick: Often, you'll be editing an article and need to make a link to a plural. For example, suppose you wanted to link "Fred Foo was famous for his study of puddles" to puddle, you could link it like so: [[puddle|puddles]]. However, you can save time instead by writing [[puddle]]s. This also works for adjectives ([[Japan]]ese), verbs ([[dance]]d) and any other suffixes or prefixes. It does not, however, work for some irregular verbs ([[try]]ied does not work; you have to do [[try|tried]]).