For the most part I consider myself super lucky in the sleep department. I go to bed roughly the same time every night, fall asleep within about 15 minutes of turning out the lights, and usually get about 7-8 hours of sleep.

Sometimes I'll wake up to use the bathroom, and lately I've been waking up for a few minutes at 3 am every morning, which is weird, but I always get back to sleep easily after the odd wakeup. Waking up is harder in the winter when sunrise is later and I need to get up in the dark, but it's not a major issue.

A poor night of sleep for me is either one where I wake up more than a couple times (usually because I overdid it at the gym and I'm crampy/sore, or because my apartment is unusually cold), or any time I get less than 6.5 hours of sleep.

I don't do anything special, just follow all the usual boring sleep advice: I don't lay on my bed unless I'm going to sleep (mostly), I go to bed and wake up at the same time most days, and have a set routine when I wake up. I exercise daily for 30-60 minutes, don't drink coffee after noon, and if I'm drinking alcohol, stop drinking a few hours before I'm going to sleep.

[Edit: I should add that when I was younger, I could drink coffee or alcohol at any time of night and still sleep well. That has changed as I've gotten older]