I know it's tempting, but avoid sodium. Before and after surgery - alcohol likewise. I know a Californian surgeon who's definitely done the faces of anyone you've seen if you've watched prestige TV, and they are adamant about not ingesting salt before surgery as swelling will affect how precisely the surgeon can work on the cartilage, bone, etc itself if swelling is exacerbating this.
other tips -
protein is key for healing. yes, it's difficult to ingest protein if you're talking facial surgery, but... this may be a case where you'll have to put dignity aside & blend unsalted chicken, tuna cans, etc like baby food. i have a friend who did this, had an awesome result & I followed suit, and I don't regret it.
avoid milk products and straws. milk can heighten mucus production (also a note from another well-regarded PS). if you've had, like, body surgery, this is irrelevant, but for facial surgeries...yeah.
everything everyone has said about it being totally chill to wear a hat, mask and sunglasses when you're ok to walk is true. apkujeong is full of ppl sporting the after-surgery look and no one blinks an eye, so shop and people-watch to your heart's content!
I work adjacent to an industry which places emphasis on appearance (being vague, sorry!) and am subject to such requirements myself. also, I like looking elegant and pretty -- superficial like that!