Mostly the former. I think I would be very good at helping someone develop an original story into a treatment and eventually a script, or adapt a book. I think I would very good as well at helping someone take a script they have written but needs someone to collaborate with to bring new elements, views, etc. to the script (ie. I'm sure many of us have read scripts that have good premises/story but bad execution or bad translation into a screenplay).
I don't want to sound like I'm full of myself or talking big with nothing to show for it and I'm very open to working under someone's control and direction and bringing what I can to the table.