You need to first look at your prior year on a month-by-month basis.  This will identify your outflows (cash) during your strong and weak months allowing you to hold-back what you'll need during the lean months.  With this in mind you can set up a monthly budget in your accounting software package.  If hold back the shortfalls that will occur during your strong months you should not have a future cash flow problem.   However, build in some fat of at least 5% extra for unforeseen increases.  Throughout the year take a little extra every month and build up a reserve for the future.  This will allow for any problems (building repairs, increase costs of purchasing inventory or slowdowns in the economy effecting your business) to name a few.  If you follow these steps you'll be 10 steps ahead of most small businesses.