There are many creative garden designers in WA. With all the things you would like to achieve, a professional will be able to advise on how to make the necessary changes. Yes, it costs for the advice but it also avoids making costly mistakes.

Hi Jase, 1. I would level out the entire backyard salvaging only the tree in the corner. 2. I would then use the bricks from the current retaining walls as pavers for a BBQ area with a pergola.(Looks as though you already have one in photo #1) 3. If you can't remove the existing fence (you should because it looks like asbestos) - then I suggest you straighten it up and paint it (asbestos proof it) then place a lattice in front of it and grow a climber. 4. I would then use the grey cement pavers to create a pathway with mondo grass in between directly in front of that area in #3 leading to the tree in the corner. 5. Using some of the cement pavers I would create a place under the tree for a garden bench and some beautiful pots with flowers. 5.The grass I would use in the newly created space is Sir Walter. Hope this helps - good luck!

Agree, raised planter boxes, just make sure they're deep enough to get some decent planting into them. And as mentioned above, if you make them 400mm - 600mm high, they will be high enough to sit on, or you can create seating nooks withing the built up beds. Also look at changing the colour of the fence, or growing something to screen it.

The leveled area that you propose has not considered drainage. Looking at the photos, there is an existing swale that is catching excess moisture and then enabling a percolation effect. If this was my site, I would leave as it presents - this is the sustainable way. You can plant into the slope down to the swale. But use plants here that will tolerate wet and dry. And do not bring in extra soil - use what is on site. This is the sustainable way, and your garden will last. The area adjacent to the house (1.2 meters wide min) I would put down a base with fine aggregate over the top. You may not even need garden edging if managed right. The slope can have plants with a mixture of heights - avoid the Acacia recommended; the A implexa suckers and the Hakea salicifolia will get far too big for the space. Better choices are some of the smaller shrubby bottlebrush and maybe grevilleas. A couple of smaller trees could be considered but not lumped at the top. Finish with a few native lomandras all the same variety to add a textural contrast. Clean up the concrete mess left by the builders - this is extremely alkaline. The aim of the planting should be to hide the fences - and the roofline over the back fence and provide diversity of plants for birds. Remember the obligatory bird bath.