Maiko lost her job and she was forced to sell a rental property because she did not have other funds (liquid, emergency, etc) available to meet her financial obligations- What financial principle best applies to this situation?

What is the most important step in financial planning?
Monitoring Your Financial Progress. Regular communication and follow-up are important steps in the financial planning process. In fact, creating the plan is really just the first step. You'll have ongoing contact with your planner to find out whether you are on track to meet your financial goals.