Here's what I've done:
restricted my caffeine intake to about 3 cups of tea a day, and only in the morning/early afternoon
Put single duvets on the bed so that DH's sleep movements disturb me less
Worn earplugs (can't always face this, as I find them uncomfortable, but good if DH is snoring!)
Got up in middle of night and decamped to the spare bed (change of scene quite often works for me, even though the spare bed is a slightly uncomfortable sofa bed)
Made DH sleep on spare bed if I'm really knackered
Got a radio with a sleep timer, so that I can drop off to it
Figured out a scenario in my head that stops my mind whirring - then i concentrate on thinking about it. As long as there is nothing else going on (noise, discomfort etc) this can help. My scenario is "me walking to the shops to buy something" - really boring, which is maybe why it works
Sorry if all these things are obvious. The thing that seems to shock people is that I like to sleep on my own, despite being happily married. This seems socially unacceptable to people, although it's not uncommon in other countries. And I've heard that the latest trend in posh housing is for new builds to have 'his' and 'her' master bedrooms, so maybe things are changing (for those who can afford it...)