asalaamu alaikum brother,
Fajr is my favourite time of the day / night and even though I take my meds at night, which make me very drowsy, I am often awake in time for Fajr, even after a very late night . I think about waking up at a specific time and look forward to it, and find that if I am positive about waking up early then I am more likely to, than if say I think oh no I have to be up for fajr in 3 hours lol. My husband sets an alarm just in case, and if I'm not up he kicks me out of bed lol. (not literally lol) but I rarely need it, especially if I have made du'a asking for help waking up in time.
think positively, and prime your brain to wake up at a particular time ( think a specific time eg 5am or 4.45am) and you will be more likely to awaken. Find someone who will get you up if your alarm fails, or if setting snooze is a oprblem put the alarm clock so far away that you have to get out of bed to put it off.
HTH