you can farm up to 30 greens daily (by watching vids)
then you can buy 2-3 young expensive fast trainers 4*, train them and increase more their value and sell them at the end of the season as 5*.

If you 're struggling and you that you 're not promote to next CH.L., stay in the same lv (loosing on purpose and finish 10th) and save sources for one season.