It takes a lot of missions to level up nowadays but eventually you climb as long as you don't stop. I am now just one level away from unlocking the Country Festival Auditions mission.
Looks like a pretty decent one for just two hours but whether you earn on the high end of the range or low end of the range will make a big difference.
The other thing I need to work on is Ego which i will do once I reach level 125, I think. I am thinking whether to switch to missions earlier so that I bring the ego down and also level up faster.
Ego is pretty high at 8% and eventually it does catch up with you if you don't do music lessons or buy skill cards. Took about 1 month of missions before it started to creep up. Hopefully, I will be able to catch it before it goes up to 10%. That said, it doesn't have a major impact on earnings in my opinion but it definitely does reduce it a bit.