What is a Member's Bill?
Most of the time, Parliament deals with government business. But every second Wednesday, they have a "Member's Day" - a chance for MPs of any party to put forward their own legislation. Those bills are known as "Member's Bills".
Originally, bills were done on the basis of "first come, first served". When there was a space for a new bill on the Order paper, you had to camp outside the Speaker's office all night to be first to hand it in in the morning (Jim Anderton was particularly good at this). Now, they have a ballot system: each MP who is not a Minister can submit a bill, and they do a random draw to see which ones fill the available spaces (of which there are a maximum of four). There can only be one bill on each topic, so duplicates are resolved by pre-balloting (this is usually unnecessary).
So, getting an MP to sponsor a bill is only part of the struggle; there's also a large element of luck involved.
The ideal Member's Bill
Member's Bills are usually short and simple. The ideal is two pages long - including the explanatory note. It must be extremely simple to understand, and therefore have a clear and limited aim - like repealing blasphemy or sedition, for example (for professional examples, see Jeanette Fitzsimons's Resource Management (Climate Protection) Amendment Bill, or Gordon Copeland's New Zealand Bill of Rights (Private Property Rights) Amendment Bill). They don't aim at fundamentally changing the world - just one small piece of it.
Some bills are longer - e.g. Nandor Tanczo's Waste Management Bill - but they require significant drafting resources, and might be beyond us.
So, think small. Think incremental. If something can be done in a number of independent steps, think about breaking it up into seperate bills which can be submitted individually. This is obviously less satisfying than a single "big bang" - but its more likely to succeed when each small change can be assessed and argued for individually on its merits.