Most lawyers have some sort of engagement letter for new clients, but few realise that it is one of the most effective ways of ensuring payment.
A good engagement letter explains to your client what you will (and won't) be doing for them, how much it is likely to cost, how they should pay you, what happens if they don't pay you, and how you get “divorced” if it comes to that. There is a good example of an engagement letter (as used in the UK) on www.xpressdox.com under “View Demo” on the first page. Feel free to re-use the parts of that document that apply to your practice.
An extract from the Business Advice for Law Firms e-book by AJS