Lifelong severe insomniac (sleep onset mostly) and cured myself pretty much entirely over the last year or so. My suggestions in order of what I perceived to be their cost vs effectiveness ratio:

1. The Sleep With Me podcast, especially if you struggle with racing thoughts (if you have a partner who can't stand hearing this, the Ozlo Sleepbuds are a good if imperfect solution)

2. Stellar Sleep, an app that delivers CBT-I, evidence-backed cognitive therapy for insomnia; this reset my sleep clock in about two months, which is now maintained by the other items on this list

3. Eight Sleep mattress pad to keep temperature low during sleep, especially on warmer nights

4. Manta Sleep Mask to get full light blackout

Also I've definitely just doxxed myself. But worth it to help some fellow insomniacs!