By citing two of the most common "sticky situations" you're most likely to encounter in your career as a freelancer, you now have the idea that you need to alert and prepare yourself. There's no need for you to push the Panic button should you find yourself in a tight spot.
Let me orient you towards the last one, and this is especially tricky:
Sticky Situation #3: Unreasonable Demands Made by Your Client
To illustrate, an unreasonable demand could be a client asking to be billed after you dispatch the finished project to him, either through snail mail or email. And then, as soon as you send your invoice, your client contacts you and asks for further revisions in your work, otherwise, he shall withhold the remaining balance.
The danger: The worst that can happen is for your client to get you to cave in to his demands, and you're pushed to the losing end of your transaction.
Your way out: If you have a copy of your Freelancer's Contract, calmly explain to your client that you are only allowing a certain number of rewrites within a given time frame, and should your client end up dissatisfied with your finished work, tell him that you'll revise your work after he has paid an additional fee.
Now, you might think that you're being too harsh by asking for more money, and be prepared for objections and complaints, but this is not a financial issue. Rather, it has more to do with your professional integrity. You're sending off the signal that you value not just your skills and creative talent, but your time as well.