Dun and Bradstreet Small Business - Keeping up cash flow

Complete your work on time, every time.

When you accept an order from a customer, send an acknowledgement stating the expected completion or delivery date straight away. This sets an expectation for your customer and also gives them an accurate time frame for when they need to pay you. If there are delays in completing the requested job that could impact your customers' business. Worst still this will in all likelihood increase the risk of returns, or non-payment.
Send out your invoices in a timely manner.

There is nothing worse than completing an order or assignment, and not sending an invoice for 30 days or more. The longer the time between the completion of the order and billing for the merchandise or services, the harder it is to stay top of mind with the customer and the more likely it is that the perceived value of product or service will have fallen.

Set aside one morning or afternoon each week to keep a steady flow of invoices going out the door. It's usually not practical to send an invoice with every completed assignment or shipment, but be sure to keep current with your billing to customers. The sooner you send an invoice, the sooner you can expect payment, or you will have a better chance of resolving any issues regarding this customer before you accept another order or assignment.

If your assignment is for services provided on an hourly basis, be sure all your employees or other services account for their time so you can accumulate these costs and send a complete bill. If the project will extend over several months, send progress bills at least monthly. It may be difficult to be paid for unbilled services if you send out an additional invoice months after the completion of the initial customer order, just because your internal records are behind schedule.
There is nothing wrong with saying no to somebody who already owes you money

No one wants to say "no" to potential business these days, but be careful when you accept an additional order from a client who already hasn't paid. This practice could make a small customer problem into a much larger problem and suddenly you could find that your business is the one in trouble.
Be flexible and accept payment terms from your clients.

Review your Accounts Receivable outstanding balances and keep in contact with outstanding customers, or outsource that service to a company like Dun & Bradstreet. A series of smaller payments may be easier than the payment of one large outstanding invoice. If you do accept a payment plan, make sure you have it in writing, and be sure to enforce the terms, or you could be right back to where you started from.
Behave in a friendly and affable manner with your clients - even in the face of adversity

You may not be able to send out a hand written card or call each client personally, but be sure to let your customers know you appreciate their business. Say thanks every now and then and even when you may not be having the best day, never, ever take that out on your clients.