Australia has nice examples of painted and rendered Art Deco homes. If it was a different kind of brick I would say keep it, but I think painting/rendering would really brighten the place. I love the windows. Although all pics here don't exactly match your style, they are all of that era. As mentioned in above comments, there are mix of landscaping styles that suit from conifer/gravel/grass to cottage rose garden to an Australian native garden. Do what reflects you and how much time you have for your garden.

Great improvements! I'd colour match to that lovely pale taupe brick in your brickwork Perhaps half strength dulux ricochet or full strength cb dune or wallaby

Are you sure the roof is stainless steel?? That is VERY expensive and only used in very exposed corrosive coastal locations since it lasts forever. I think it might be Zincalume, a low cost but very durable and very common roofing material that has a light silvery surface and should last for 50 years. Definitely do NOT paint the roof black (or any dark colour), it would add more than 10° to the internal heat load, and you would have to spend so much more on insulation and on-going AC costs just to get back to where you are now. Have the roof checked and repaired by a roof plumber instead. If it's an old leaky galvanised iron roof at the end of it's days, replace it with zincalume. The porch roof looks like it needs replacing, but I would replace it with new roofing, possibly the insulated sandwich panel kind, that has a smooth white underside, then add a gutter to the front edge so you don't make your visitors walk under a waterfall in the rain. The canvas awning suggested earlier would not last as long without looking tired and would require the removal of existing roof structure, so I think it would be the more costly option (and you would still have the waterfall problem). I would leave the front fence as is, it ties in nicely with the house, but trim the tree. The back deck could easily be roofed to match the front, and be more useful to tenants with weather protection. It would be good to make all trim colours the same, and against the cream brick I think the dark grey you have on the front door and columns works quite well. I would make the other windows and trim, as well as the weatherboards over the back door match that if it just involves painting. However, it's not essential and if it means changing powdercoat finishes it would be too costly to be worthwhile in a rental.

I really like the first picture, though it does look like it's due for a repaint, and while I like the colour scheme, if you're bored with it I suppose it's an opportunity to change it. In the second picture the green trim and the detail above the front steps stands out and looks dated, and the landscaping doesn't enhance the house.