(if (condition)  ;; <- must be when, not if!
    (do-this)
    (do-that))

I didn't find that to be a common problem when writing Emacs Lisp at least. The "misleading indentation" warning is relevant thre. If you enter the above code into Emacs, auto-indenting as you go, it will indent like this, making it obvious you meant `when`:

  (if (condition)
      (do-this)
    (do-that))