You can be very successful without paying money or watching 30 ads per day. All you have to do is pick a formation and then highlight the 4 most important positions in that formation and buy 4 players to fill in. These players will be key so you have to make sure they are good, I'll advice buying recommended players or Academy players not auction players. You can boost these players to 120% with your startup resources and then it will take you about 240 rests per season that is just about 8 videos per day coupled with the amount you earn from making substitutions and other means, it would be more than enough to maintain these players at 120% every season until they are maybe like 28yo when training reduces drastically.

Then you can buy the remaining 7 players to complete your squad. Then you must get many one star players in other to manipulate the draw at the end of the season (I'll suggest that you search the forum for more on that). If you sell off your 7 unimportant players at the end of the season your team quality will drop to less than 30% this will get you into very easy competitions.

I can guarantee that if you do all these you will win the treble every season and your team will be far more successful than many 7-8star teams