What are the best vocal lessons for mezzo soprano 

I'm really wanting to strengthen my head voice.

I'm struggling with picking a song. I usually go through one of the beginner warm-ups that you posted and that's it or the warm up and then one of the videos from tricks and techniques. I don't really know how to work on a song 

I am feeling discouraged about singing right now. I want a better voice and a stronger tc

One more question, I'm trying to go through the 30 day singer course I am wondering if I should do a beginner warm up and then play one of the videos or just do the 30 day singer course by itself without warm-ups?