Well, since cash flow is the amount of money that you are bringing in, minus the amount of money you are spending.
The best way to make sure you have enough cash flow to cover your expenses is to make sure that each month you are spending less than what you are bringing in. If this isn't happening, either cut back on expenses or find ways to make more money.
A good example is if I'm spending $1000/month but only bringing in $900/month, then I need to figure out ways to bring in $100 more per month or reduce my expenses by $100 per month.
An example of how this applies to real life situations would be if you're looking at buying a car and want to make sure it's affordable on a monthly payment basis. You could take into account the cost of insurance and maintenance and see whether or not it's something that can fit into your budget each month without taking too much away from other expenses like food and rent.
