1. Traditional guidelines call for displaying the flag in public only from sunrise to sunset. Sunset right now is around 8:30 p.m.
2. You can keep it up after sunset, but you need to have a light on it. My floodlight on my flag is on a dusk to dawn timer, and I use an LED spotlight to save money over a traditional light bulb.
3. According to the Veteran's Administration, it should not be displayed during rain, snow and wind storms, unless it is an all-weather flag. If a storm is coming, I try to take mine down, so it doesn't get ripped off my house.
4. It should be raised briskly and lowered ceremoniously.
Also, if you have a flag that you can't lower to half-staff (hopefully we don't need to for a while), check out what to do in the video below: