Cash is King
Cash is everything.
One of your key dashboard indicators each week has to be cash.
Invoice as early as you can, forecast when payment will be received.
If you are dealing with large corporates make sure you get the Purchase Order number and quote it on your invoices.
State your payment terms, chase as soon as payment is missed.
As Theo Paphtisis says:
"A lack of cash is like a heart attack for a business. If you can't pay the rent you shut down, just like you would if your heart packed up. You're finished. If you can't pay the wages, it's all over. Don't be without cash. You can live without profit for a while, but not without cash. It's very basic and simple advice."