I think the most understated and most under-exercised ('scuse the pun) tip for sleep is actually exercise!
The benefits of, say, an hour's walk 4 times a week can contribute the following: relaxation, time out for your brain, some time in nature where people can feel more balanced, reduced stress, proved help for depression and anxiety, improve your health and muscle tone, improved attitude generally, physical relaxation (not just mental).
By yourself, or with a partner, friend or pet... all great. Just make sure you're not reliant on other people to actually do it... this is one of the reasons the plan fails. Plan to go by yourself, company can be a bonus.
Sounds too easy doesn't it? Let's not forget the basics. It doesn't have to be rocket science to start re-gaining our health and happiness in very simple and constructive ways.
If you're not doing this, don't knock the idea. Exercise is fundamental to a great life.
And I recommend walking as the best idea.... if it's easy and doesn't stress you out, you're more likely to do it. Be the tortoise not the hare... by consistently moving forward towards a better night's sleep.
Ritualise the process, so it becomes second nature. e.g. same time every day, same path every day... make it so you don't think about it, you just do it. Our mind talks us out of a lot of great things - don't listen to it's chatter about not walking!
After a while, when you have developed this habit, you might add on another form of exercise (note I'm not saying "replace") like tennis or belly dancing, or cricket with your mates - something you could enjoy socially and make a few new friends even while your doing it.