I've recently started to sleep earlier in order to improve my sleep quality, and some of the things that have helped me are:
1-Having a routine, for example, I prepare the next day's clothes, I make a to-do list for the next day and then I read a book. I try to do this at a similar hour, which has helped me to sleep faster.
2-Trying to be exposed to as much solar or artificial light as possible throughout the day, which basically means to go outside for a while everyday.
3-At night, avoiding light or smartphones. It's kinda hard to don't be exposed to light at all but I try to reduce it and I also don't use my phone after 9pm and If I have to, I use an app that reduces blue light.
4-And last but not least, sleeping and waking up at a similar hour everyday, even weekends. I don't mean exactly the same hour, and this helps me to not be so tired all day and also to sleep faster.