Rule No. 1: You are the ruler of the shade.
The window shade breeds contempt and conflict among plane passengers. Some could never imagine shutting the thing, blocking the window's best feature: the ability to see outside. Others prefer to keep it down, opting for better sleep and better views of entertainment systems. Both parties have a point.
Because you selected - and perhaps even paid extra - to sit at the window, you have the final say in whether the shade stays up or down (excluding times flight attendants instruct you otherwise). That being said, just because you're the boss doesn't mean other people will respect your authority. Flying is generally a communal activity, and unless you're one of the incredibly lucky souls to get a row to yourself, neighbours may ask you to adjust from your own shade preference.
Some questions to keep in mind before you make that decision: Is the person asking you to change its status a child? A parent with a child who's trying to sleep? A person who has never flown before? An anxious flyer? Also consider your route. Are you flying into a new time zone, especially overseas? Controlling the window shade may have an effect on fellow passengers' internal clocks, as well as yours.
Ultimately it's up to you, the occupant of the window seat, to decide whether you'll be a benevolent or omnipotent ruler.
Rule No. 2: Limit trips out of your seat.
Our human bodies are not always easy to control. There's nothing unethical about needing to use the restroom frequently on a flight, or wanting to stand up and stretch. But if you're a person who fits either of these travel styles, don't book a window seat.
Sometimes requests to exit your row have nothing to do with bodily functions. If you pack your carry-on bag strategically so you have everything you need within reach when you're locked in by the window, you can avoid making everyone stand while you grab your headphones/neck pillow/melatonin/beef jerky packed in the overhead compartment.
Particularly given the tiny nature of seats in economy, it's a hassle to squeak in and out of airplane rows these days. Don't plague your rowmates with a barrage of requests to leave your seat.
Rule No. 3: Time bathroom breaks with the middle seat or aisle.
Per the rule above, the way to be the most considerate window-seat passenger is to follow your neighbours' lead. Watch for the opportune time to make a break for the lavatory: when the middle is exiting, too. That's your queue to get up, capitalising on everyone having to rise, anyway.
Rule No. 4: Lean into the window.
This rule is ordained with the middle-seat passenger in mind. While you're tucked deep, deep into the row as the window-seat holder, you're also often blessed by a little alcove between your armrest and the window. Take advantage of those extra inches by leaning into that nook when possible. You'll alleviate some of your squished neighbour's misery in the process.
Rule No. 5: Overcome claustrophobia.
If you're claustrophobic, this position is not for you. The window is for people who don't mind huddling up in a confined space for long periods; people who understand that with great power (controlling the shade) comes great responsibility (not getting up unless everyone's getting up).
The view from the window may be comforting if you're claustrophobic, but once you look ahead or to your side to see how you're crammed like a sardine, you could lose that sense of relief. Opt instead for the aisle, or, if your phobia is stemming from a general fear of flying, turn to apps that help nervous flyers.