How can I emulate Orderless attribute?

Suppose I want an expression to automatically sort its arguments. This can be done via

SetAttributes[f, Orderless]
f[3, 2, 1]
(*output is f[1, 2, 3]*)

Just as an exercise, I want to emulate this behavior myself with

f[x__] := f[Sequence @@ Sort[{x}]]

which doesn’t work due to infinite iteration.

I would be enlightened if anyone can show me an example how to implement this.

f[x__] /; ! OrderedQ[{x}] := f @@ Sort[{x}]

call : f[x__] := Block[{f}, Sort[call] /; ! OrderedQ[call]]