Hey there! I also take a while to sleep, and I’ll agree with most of what dB_FTS said, though I am just too addicted to technology to go without it an hour before sleep 
Repeating mantras can also be tricky for me, so there’s two things that I found helped. One, at the beginning of the night I use autosuggestion instead of MILD. Basically, instead of trying to make the thought the last thing I think before I sleep or whatever, I just repeat it until I feel like the intention is set. Think of it like reminding yourself to do homework or pay a bill. You don’t have to constantly think of it, you just need the intention. And you don’t have to do it just when you go to bed, you can do it throughout the day.
Even if you use an alarm, I’d still suggest trying any techniques 4-6 hours after first going to bed (I find 4.5 hours is easiest for me to fall asleep again). It just makes life easier.
All that aside, I also suggest you check out this topic from the FAQs and tutorials section.