One of the most helpful things with our business is having a cashflow projection statement. We currently have tweaked the 12 month cash flow statement from this Score page
https://www.score.org/resource/business-planning-financial-statements-template-gallery. Cash is king with a business, and knowing how much you have coming in and going out is essential. This cashflow statement we use in conjunction with our P&L and Balance Sheet.
A cashflow statement is helpful both when you're starting out to see if your business is financially viable and when you're more established. If you have a seasonal business, it can help you know how much you need to earn in your busy months to tide you through the down times.
One of the biggest challenges with a cashflow projection worksheet is overestimating your income and underestimating your expenses. This will probably happen anyway, but try to be as realistic as you can. In my opinion, it's better to underestimate your income and overestimate your expenses for projections.
Our cash flow statement helps us make decisions on how much money we can set aside for business savings, if we're earning enough to hire another employee, how much we can take out of the business to pay ourselves (beyond our basic payroll income), if we project a leaner time is coming so that we can prepare, etc.
Even though we try to project out for 12 months, our cash flow statement is more accurate for 1-3 months. We adjust it as we get new clients, lose clients, have more expenses, etc. We also keep a close eye on our bank accounts since even if we projected income coming in a certain month, some clients may pay late, we may have an unexpected expense, etc.