How do you know if you are doing the lessons correctly. I noticed a pretty quick improvement in my singing just with posture and breathing, I have noticed some strength in my voice at certain tones but feel like things have stalled. I am maybe 3 months in and practice about an hour a day 4 days a week. With the drills my head voice at high tones has not really improved and when I practice those high tones it does not resemble singing. 

Hi, Jason! I recommend sending in a video for feedback so an instructor can hear your concerns and give advice: https://www.30daysinger.com/feedback.