How can I keep my mind from wandering so I can finally fall asleep?

Control your thoughts, get a grip of them. Meditate and even talk to yourself if your thinking is too loud, until you fall asleep.

Try keeping your electronic gadget away from yourself at least half an hour before going to bed. Second method one can try is by doing slow breathing exercises for 10 minutes before sleep. One can also go for meditation as it relaxes you mind as well. While doing meditation ,try putting some calm music which will help you focus more. Try to put your thoughts on pen and paper, whatever issue is bothering you. And the last thing is try getting early sunlight , it is beneficial for your health as well. Hope it helps ! :)