If you're going to be doing much trading, set up an account with Computershare online so that you can do all the details online. That involves a bit of back and forth with paperwork, but means after that that you never need to fill those forms in again (unfortunately the same can't be said for Link Market Services, or the other various registries that some companies use).
If you're fully registered with Computershare, you can do the TFN, direct credit authorisation for dividends, email address, and selection of annual reports, etc. all online. Beats getting dividend cheques in the mail, and in fact some companies won't send cheques any more.
The main negative is that the Computershare site is often slooooowwww, and I often can't log in at all in the evenings and weekends. And when it comes to updating email address and report selection, you don't get a summary of just the ones you haven't done already, like you do with TFN and direct credit selection, so have to manually go through each share you've ever bought to find the ones you haven't done.
And the other problem is that even if you intend to do everything that way, you can't stop Computershare sending you the forms. Apparently they're legally required to, so you just have to do the short letterbox to bin transition every time.
GP