We recommend you to start little by little reinvesting your money in basic furniture in all your rooms, like nightstands or TVs. Don’t waste your little progress on huge investments! 
You will receive your profits every hour, so take in mind the staff salaries because they will be paid automatically from your money counter.
If you are in the red, take a deep breath, and study the situation. Sometimes it's better to temporarily close a service or reduce its staff until the better times come back. Pay attention to objects which will give you better profits and establish priorities accordingly.