Update for season 27 (my 7th season with this team):
I have made the playoffs in my first season in Div II. Despite doing so, this has been the most challenging season thus far. I had to battle injuries and plan out a strategy to hone in on the playoffs.
I sold off all my players above age 33. However, I have found very little market in USA in which to add players that can play in Div II. My homegrown trainees are now starting to finally be useful, however in order to make them really useful, I need to train at PG which will make winning next season a challenge.
The best suggestions I have for newbies:
Do not tank. I tested it out with my Utopia team and it was a terrible decision. The economy is terrible. Even with pumping a ton into my arena, I can't even come close to the top teams in tickets. Also the draft is a huge gamble. So its not worth it. Tanking in Div I or II can make sense, but ultimately it will set you back 1-2 seasons.
Managing the economy in the end is what leads to wins. Once you have a finished arena it comes down to how well you can balance spending vs saving. You still have to use strategy to win games, but economics is the key to a solid foundation.
Building a team is secondary IMO. Sure it helps to have players that fit their position. But in the end if you can afford a roster that is 20-40% more costly than the second place team, you are going to win a title in most cases. How you go about getting the money to do so, well that is what makes this game a challenge.