My suggestion is to wait a while before to fight seriously, if you really want to make money. You've to learn how to mix the weekly income/costs and be competitive at the same, you've to expand your arena and in which players to invest for train them re-selling with profit.
Question mark, cause I've never played in this way, is having one of the strongest teams in your country, for sure you'll have more revenues from arena and better merchandising so maybe it could be possible to make money in this case too (if you still are able to respect salaries vs incomes)
1990-2022 Stalinorgel - https://www.youtube.com/watch?v=pV-Xppl6h8Et