What is your climate, and the orientation of the spaces which is important to know for things like hot afternoon sun etc?

When you say 'low maintenance' just how low maintenance do you mean? If you want something lush it won't completely look after itself so you will need to be doing some maintenance. There can be a fine line between lush and overgrown, especially in favourable climates. I mean no-one ever says 'I enjoy cleaning the bathroom, my weekend hobby is bathroom cleaning' but they say 'I'm not a gardener, I don't want to waste time on weekends maintaining the garden'. It's particularly sad when they have bought a lovely place presumably in part because of its kerb appeal and a year later you see that value is gone from the property. If you are an inexperienced gardener but willing to do some work as long as the plants are hardy and reliable and the work is not too time-consuming that's different to wanting to install landscaping and then ignore it. 'Low maintenance' and 'water feature' aren't words I'd put together. It might be within the workload you envisage, but let's get a clearer idea of that before we go any further with specific suggestions.

Block is north east facing so sun starts in the back yard and will curve over towards the staircase side garden with afternoon sun at the front of the house. The neighbours are quite close so lots of shade over the secret garden near the kitchen.

In Perth WA so it’s very hot here in summer - today is 28 degrees and it’s only spring!

Hardy and reliable plants yes - I like magnolia, bay leaf, jasmine, peace lily, plum trees for their spring blossoms,

Philodendron and heliconia I like too. Not a big fan of frangipani trees. No large palm trees and no bamboo

Hi Triz
Gorgeous house, a few inspiration photos for you,side path, feature wall and back garden

Haha, first thing I pictured was palms and bamboo (not the running kind) but I waited to find out the climate.

Ornamental fruit trees also have great autumn colour, but that means dealing with the leaves. So again 'deciduous' and 'low maintenance' aren't words I would put together.

Just a few for the front, even a water feature at front door, you could use magnolias in place of ornamental pears to keep an evergreen look, pleached Lilly pilly underplanted with hedera, check Peter Fudge, Dean Herald, Jack Merlo for inspiration.

Thanks for the inspiration pics :)
Doesn’t lily pilly require significant maintenance to shape?
Whet would you recommend for the feature secret garden to fill the space? Tree with shrubs, water feature? Not sure where to start....

Julie Etsy are the trees in the pics you sent..? And the grass looking plant below please...?

The pics show ornamental pears in the backyard landscape, these are deciduous but incredible in all seasons, alternatively you could use magnolias, a tough grass like plant is lomandra, Lilly pilly does need pruning to keep its shape, hedera is a good ground cover, a beautiful modern bowl or rendered water feature in your secret gardens would look gorgeous or even a teddy bear magnolia .

"Doesn’t lily pilly require significant maintenance to shape?"

That's why I was trying to find out what you mean by low maintenance. You have a small suburban garden so finding a variety of tree that will not require any maintenance to keep it to a suitable size is a challenge. So there's a question of whether you'd rather compromise on the plants or the work. I do think aesthetically a vertical feature would enhance the house.

Macyjean where do you recommend the vertical feature go...?
Yes trying to make sure trees aren’t too large they cause damage to the property via root system and/or branches or fruit/nectar falling on the roof/gutters/paving.

Definitely will be doing some gardening and where possible incorporate plants that are edible and give back

Thinking bay leaf could be an option...?

With the secret garden if I go teddy bear magnolia how do I layer plants to give varying height and colour while spacing them out for future growth?

Is there a rule of thumb with number of levels/layers?

What’s the rule of thumb for spacing of plants?

Want it to look complex and stand out as a feature in the centre of the home

Also question for you. Is it weird to have hydrangea and bourganvillia in the mix? What’s the rule with plant type and style?

"Macyjean where do you recommend the vertical feature go...?
Yes trying to make sure trees aren’t too large they cause damage to the property via root system and/or branches or fruit/nectar falling on the roof/gutters/paving."

Somewhere on the left, but start with hardscaping, driveway, draw in underground services, think about what sort of footpath you want. I agree that it might be well worthwhile to get a landscaper to draw up a plan.

"Thinking bay leaf could be an option...?"

I remember going on a garden tour of a property with a park-like garden featuring large trees and the guide pointed out the bay tree and said people don't realise how big those get. There might be dwarf varieties these days though?

"With the secret garden if I go teddy bear magnolia how do I layer plants to give varying height and colour while spacing them out for future growth?

Is there a rule of thumb with number of levels/layers?"

Just my opinion but looking at your photo and for ease of maintenance I think the magnolia with an underplanting of lomandras or something like that would be plenty. I can also picture three layers with flowering shrubs in between but I think they'd need regular pruning to look good. Lomandras don't need much attention, it's recommended to cut them right back every few years to rejuvenate them but it isn't crucial, whereas if you're going for a certain look with shrubs and don't stay on top of the pruning they can look quite scrappy and if you prune too hard they can take a while to recover.

"What’s the rule of thumb for spacing of plants?"

I think there might be some kind of general rule of thumb based on mature width? But I'd base it on the plants you choose. The label sometimes recommends the spacing, or if not the growers' websites have more information.

Got a few quotes for landscaping and the average is $2k for a design does that sound rights....? I could get the garden plants and hardscaping done for that much so not sure it’s in budget... any other way I can figure out plant selection, drainage, spacing etc using a more cost effective resource?

That does sound about right for quality plans, check in with your local nursery for advice on plants that suit your area, check with a landscaper for advice on paving and drainage, to save money do the research, check for apps that let you design your own garden and use Google for research on designing your own garden, if you decide to do the work yourself that will save $ also a watering system will save on time, think soil, mulch, turf laying but if you have willing helpers that will save $ too, but have a plan otherwise it can be disappointing if it’s not what you imagined.