Perhaps the most complicated aspect of making a garden is designing the planting. Every one of us approaches it in unique ways, and there is no right or wrong way of doing it. Designing planting involves having a good vision of how you'd ideally like things to look. This is the most brilliant bit about gardening – seeing how other people do it.
It is best to start with the structural elements of larger trees, hedges, topiary and shrubs, then the infilling of smaller plants can begin. This should take time to put together, with lots of mulling, leafing through books and catalogues. Internet scrolling is, of course, de rigueur these days, though I personally find books much easier to use and more informative. Given this is what I do for a living, and that people seem to like it, it's probably more useful for
