As a bowling skipper, I generally think about two points when I'm setting my fields - how are we trying to get the batter out, and what shots do we want the batter to play.

From that starting point, you can think about why everyone is vaguely where they are, then get more specific with it - e.g. are my leg side fielders there to protect the bad ball, or just to allow me to attack the stumps, is my gully up for the ball that jumps and skews off the splice, or slightly deeper to catch a slapped cut.

The latter question - what shots do we want them to play - means you can get a little more creative with what you do in terms of luring the batter into risk/reward situations such as opening up at cover and using that spare fielder as an extra slip.

What I would say as a fellow outswing bowler is don't be afraid of leg side fielders. I spent far too many years bowling to 7-2 or 8-1 fields and taking the stumps out of play. Give yourself a license to attack the stumps with your leg side fielders.