The best way to keep a program properly indented is to use Emacs to reindent it as you change it. Emacs has commands to indent either a single line, a specified number of lines, or all of the lines inside a single parenthetical grouping.
See Indentation, for general information about indentation. This section describes indentation features specific to programming language modes.
Emacs also provides a Lisp pretty-printer in the
which reformats Lisp objects with nice-looking indentation.