Hi @Lainey85, have a look here: http://www.immi.gov.au/Visas/Pages/309-100.aspx and make sure you read the Partner Migration booklet, that's pretty handy. It's hard for us as we don't really have anything jointly (no bills, leases or even bank accounts) so we're just using other stuff that shows we have both lived at the same address, etc. but if you have that stuff it will help. I'm going up upload a couple of photos but from what I've read they don't count for much. Basically anything that shows not just that you've known this person for however long you say but that you are actually in a relationship too.
We've been engaged since March this year but have been together just over 3.5 years so I'm hoping we have enough evidence, we just don't have the really obvious stuff so hopefully that won't hinder our application.