You might need to check NCAT's procedures, but QCAT (roughly, Queensland equivalent) requires that the tribunal decision be registered with the courts before it can be enforced - so this might be your first step. The next issue is whether you sued a company or a person (because you mention both 'tradesperson' and 'his company'). Whoever the application was against will be the one against whom the decision will be, and any following judgment once registered.
In terms of enforcement, you have several options. The courts will usually automatically give notification of judgment to the credit reporting bodies. You should probably look at an enforcement summons (not sure of NSW equivalent) first, which is an order by the court for the judgment debtor to answer questions about their financial situation. The answers from that will inform you for your next steps. If they don't comply with the enforcement summons, which is an order by the court, they may be liable to an arrest warrant being put out against them.
In terms of bankruptcy, it is possible to do so but can cost you a fair whack of money to get it done - with no guarantee that you will get paid. If he is currently operating, it can be a useful tool to force payment. This is especially the case if the order is against a company, as with a judgment you can send a statutory demand notice under the Corporations Law. If that's not complied with, it gives you immediate grounds to seek the winding up of the company. However, whichever way you're looking at going in terms of forcing bankruptcy, I suggest you seek professional legal advice before taking any steps. There are strict requirements, and potential pitfalls for getting it wrong.