Here's just a little list, hopefully something in here will help you.
1. If life allows for it a schedule is essential. Going to bed and getting up around the same time means that your body is more prepared for sleep when you lay down.
2. Don't do stuff in your bed. Get off your phone, move your laptop elsewhere, ect. By making your bed a place for sleep and nothing else you're conditioning your mind to want to sleep when you lay down.
3. Get off tech at least an hour before bedtime. Computer, phone, tv, the works. The emitted blue light (even if you have a night light filter or something similar) will keep you awake and when you tell yourself "just one more [thing here]" next thing you know it's an hour later. Spend that time instead getting ready for the next day - lay out your clothes, pre-pack your lunch, set the coffee maker, ect.
4. On the same note, don't charge or leave your phone next to your bed. Leave it across the room, screen down. My phone has a 'do not disturb' option I can schedule to be active during certain times (aka when I'm sleeping) and during that time no notifications come through unless the same number tries to call me twice in under 15 minutes, allowing for people to reach me if there's an emergency during those hours. Most modern phones will have something similar, so turn that on if you can. If you can't because of work or something else at least leave your phone across the room so that you can't just lean over and access it from bed.
5. Figure out what's keeping you awake. Don't feel physically tired? Try a small bit of light exercise before bed if the last part of my 3rd suggestion doesn't do it. Mind racing? Get a journal and write things down. I find that means my mind isn't going "Are you going to remember to [thing here]?" because it's written down in a thing I can reread the next morning and remember easily enough. Same goes for any worries or fears or anxieties that pop up as I'm trying to wind down, I find writing them out helps just so they're not in my head and I can deal with it later.
6. Try things like chamomile tea and other natural sleep aids. Do your own research and if you're taking any medications for anything else ask your doctor before doing long-term herbal supplements like that. But sometimes they help, especially during the early days of reconditioning your body that sleep time is now and laying down means sleep.
7. If nothing else is working and you can afford it try talking to a doctor. You may have insomnia or something else going on and they can give you their own advice combined with some prescription medications that may be useful in helping you get to sleep.