Go hard on the daily gather fans/money tasks until you get cashflow going. But watch your idol's stamina.
You really need to borrow money from the no-interest guy. (I savescum for a doable 'favor'.)
Optional: Spam digital release singles till your business gets to 2 star. Then only do them once a month. Business stars lets you borrow more money at a time. (Digital release singles are the best when you have no or little fans.)
What you really want to get asap is a breakroom and hire a business proposal lady for photoshoots and the likes. It is where most of your money will come from.
More idols = more business proposals you can handle. (But, once your idols get more famous, they ask for more salary when you have more idols.)
1 Break room = 5 idols