Buying server (upgrades), adding photos or movies (amateur or pro) via upload option and adding live cam rooms (with interior bonus) are the main resources for your number of clients. Additionally you can promote your side with money. The limit of clients depends on the booble server you got (1M with top server).
The growth of clients is based on your subscription price. At the beginning you should chose a price which gives you some money, but also increase the number of clients (2-3$). When the number is at max you can adjust to make more money (without loosing clients). In the end you will make 5-6M daily.
Remains only the question how to collect all that money. Simple answer. One or two times a day click at the Dollar symbol above Booble Building. You will see the amount of collected money and client growth. The amount of money is limited to daily income, so you won't receive more than 6M.