The below helpers are not commands themselves, but can be used in conjunction with the above commands.
The | character. lets one chain commands. e.g. ps -aux | grep java
The shorthand way to refer to this directory explicitly
The shorthand way to refer to the parent directory
Pressing tab will let linux guess what command/option best fits what's currently written. very useful for navigating directories and long-named files (NOTE: not necessarily tab based upon one's keyboard layout/language)
Look up the mostly likely command that matches what one typing. so if one earlier used ps -aux | grep java | less and the hit ctrl-r and typed -aux it would likely pull that command or at least the most recent one that matches