Requesting credit from your suppliers can help your cash flow, especially if you yourself offer credit to customers.
 

Any new supplier will check you out in the same way that you would check one of your own customers.  You therefore need to build up a good credit history by paying existing suppliers on time and keeping up payments on loans and credit cards.  A sole trader / self-employed person will often be judged on their personal credit history.

You will be asked for business referees:

• existing suppliers
• your bank

Therefore line up at least two exisiting suppliers with whom you have established a good trading relationship.  Note that your bank is restricted to a formulaic response and will not give away financial details.