There's a simple rule I use: -> is for maps and ->> is for collections.

Functions that take a map should take it as first argument, functions that take collections should take the collection as last argument. This is how the clojure core functions work, eg. -> `assoc`, `conj`, `dissoc` vs ->> `map`, `filter`, `reduce`, `some`.

If you follow this rule in your code, threading is nice and looks good. If you want to force different argument position, use a lambda, like so (->> coll (#(my-fn %))).

However, I recommend against it. Use a binding and then use the other threading macro if necessary.