I finally found a very useful way to practice for myself! Yesterday I warmed up for fifteen minutes doing scales, arpeggios, and long tones. Afterwards I practiced my etudes and solo, then at the very end I did another "warm up" to mostly test and improve my endurance. This practicing has been helping my higher range a lot, so I will keep it up! Unbelievably yesterday I played a C without any force. I used all of my hair and just played how high I could and got up to an E flat but first I realized I played a C and it wasn't difficult at all. Oh happy day! :)