There are 3 challenges business owners should be aware of in order to avoid getting trapped in them.
Working in your business
As a business owner, you are pulled in to work on the nitty-gritty day-to-day mundane. It is essential to pause and think if you spend enough time working 'on' your business vs. working 'in' your business.
People don't talk enough about the transition to working 'on' the business. It's not one of those things you roll out of bed knowing how to do. We give much more attention to the day-to-day, but not a framework for pulling yourself out of the day-to-day in a way that won't hurt the customer experience. You can read Michael Gerber's E-Myth to learn more about this concept.
Moving fast without direction
You can 'move fast' without direction; it's important to move fast but in the right direction, which will quickly pay big dividends.
This is not to say that direction and speed are mutually exclusive. If you have the correct direction, but are the slowest to market, you have a problem. If you are the fastest company around, but heading in the wrong direction, not going to work either. Never lose sight of the big picture and prioritize direction over speed!
The illustration from Jack Butcher brings this point to life.
If a single client makes up more than half of your income, you are more of an employee or contractor than a business owner. Diversifying your client base is vital to growing a business. A client that represents a large chunk of your business may be in a position of negotiating steep discounts. Even when this is not the case, where the client in question pays well and on time, they might feel empowered, and you may find yourself working on their terms rather than on yours.
This hurdle can be challenging to overcome, especially for new businesses. You may find yourself in this position, where you don't have the choice of being "picky", as you are trying to build your client base. Be mindful, however, that this is not the ideal structure for your business and you should work on improving that as your company grows.