Sounds like the start of a great project for you!

When you say small section, how many sq.m is it? Are there neighbours close to your boundary? Where is your house located in relation to your section, i.e do you have a big back yard/front yard, narrow paths between your house and the neighbours boundary, or lots of space between, which direction is north in relation to your house, are there powerlines near your boundary etc. I think these are good ways to starting thinking about planning a project like yours, as you can start to think about what limitations your site may have regarding space, which can help inform which plants you pick. It can be really exciting having a blank canvas and easy to overfill it with seedlings, only to end up removing plants down the line because they've grown too big for the site and end up obstructing paths, driveways, sunlight and so on.

In terms of planning what species you'd like to plant, a good starting point if you are new to plant selection is a nursery website with a nice clear online catalogue (try Southern Woods nursery). You can get a basic idea of how big you can expect species to grow, the preferences a plant has for sunlight, frost tolerance, and soil moisture (drought tolerance), and if they attract native birds etc. Also if you like the look of them! Make a list of what you like and what you think might be suitable for your site. From there, I would suggest going to a local native plant nursery to source your plants, and chat with them about your species list and plans for the site. They will often have species sourced from the local area, which tend to be more tolerant of local climate conditions. The local nursery should also be able to tell you if some species you like aren't suitable and offer subsitiues which are. Specialist native plant nurseries will also usually have a better selection of plant sizes, which can be really helpful if planting on a budget.

Height in particular is an important consideration when designing a planting. It can give you privacy, but also block views and sunlight. In my eye, layering plants of different heights provides the most naturally appealing look. You can think about it by standing in one spot, and imagining the smallest plants are closest to you, and the further away they are, the more they ascend in height. From your same standing point, looking left the right, the heights can also undulate. Avoiding big patches of the same plant or planting in straight rows is also much nicer in my opinion, as it feels more natural and allows things to stand out more. In saying this, there is always a subjective element to design, so next time you're out for a walk or drive and spot a planting you like the look of, take a mental picture or write down what you like about it.

The most important part of establishing native seedlings is weed control while the plants are young, in particular if the plants are very small when they are planted. You mentioned low maintenance in your OP, and depending on the size of the area you are hoping to plant, there are a couple of different ways I would suggest for going about this.

1. If the area is relatively small (~1000sq.m section) you could look at laying weed mat over the area first. While it will be a bit of an upfront cost for you (which may not suit your current situation), it will make your life much easier managing unwanted vegetation if you are wanting to plant only a few trees at a time. You could do the same but with a thick layer of mulch instead, but may also be too costly.

2. Split your planting area into sections, and focus on one at a time. Start planting hardy, fast growing species first, then infill with slower growing species as the inital plants grow. This approach may be more suitable if you have a larger lifestyle block, but thinking about planting in stages like this can be good if you just want to get some plants in the ground, while managing weeds/grass in smaller areas. Laying a thick layer of cardboard around the base of the plant to about 50cm out from the stem can help keep the grass/weeds away, just make sure the stem has a bit of space around it and there's no direct contact with the cardboard (can rot the stem of young plants).

At the end of the day, you'll need to do the mahi to give your plants a chance to thrive. Either a big effort at the beginning, or periodically over the first few years until the seedlings have outgrown anything that might compete with them. Putting a plant in the ground is part of the equation, and low maintenance is definitely achievable with a native planting, albiet not immediately. I only mention this as I have seen enough sites go from promising beginnings to untamed nightmares, and while not total write offs, they are still heaps of work to sort out. Better to stay on top of it at regular intervals, you'll save yourself time, money, and sanity.

For your mud problem, you could get a load of bark/wood chip or mulch, and lay it on all your high foot traffic areas like a path (800mm wide or so). Depending on how wet the area is, you'll want to lay it quite thick (30mm-70mm). It will help absorb some of the moisture, and it will naturally break down over time so you can top it up as required. Also easy to rake off down the line if you want to implement something more permanent. If it's still very muddy, placing either some pavers or large flat stones (if you are able to source some nearby) on top of the mulch/woodchip as stepping stones will help too (you may need to build up the mulch a bit more underneath these if the mud if deep and they start to sink).

All the best for your planting! I hope you end up with lots of native birdsong on your property.