In no particular order:

• being fit
• physically tired
• no booze or cannabis on nights I actually have to sleep well
• a completely dark room, no little lights on electronic devices, blackout curtains, etc…
• a bed (I won’t mention the brand unless asked) that adjusts to my sleep patterns. It measures my breath rate, heart rate, how often I move, if I’m snoring (rare), etc… It then knows how well I’m sleeping and can soften or firm up, and tilt my upper body up or down. Depending on how my vitals change it learns how best to accommodate my sleep.

If I have trouble due to stress or the neighbors are making noise I’ll throw on an eye mask and ear plugs.

I’m basically comatose 15 minutes after hitting the pillow and wake up before my alarm.