The fact that you see crtotons in old and neglected gardens in Queensland attests to their survival skills, but for best results avoid the hottest and driest positions. A little attention with respect to water and fertiliser will be rewarded. They will need plenty of light for good colour development, but some shade is acceptable and even helpful in Qld'd harsh climate.
New varieties developed for indoor cultivation in cool climates (where they won't survive outdoors) are more tolerant of low light. If attempting to grow such cultivars in Qeensland, we might expect that greater shade will be tolerated (if not demanded), compared to some of the older landscape types.
Crotons are generally not fast-growing, but this means less maintenance over the longer term. For a fuller effect faster, cheat by planting 3 or more in a group.
In old gardens, you sometimes see crotons growing 2-3 meters high. However, if left alone like this they end up the foliage at the ends of the branches with bare trunks and woody stems showing below, which is hardly attractive. Cut back occasionally to keep bushy, with plenty of vibrant foliage at eye level.
Some varieties are naturally shorter and more compact. They'll need little if any pruning, except to improve shape.
Planted in front gardens, along driveways and around patios, you won't have to worry about rampant growth getting in the way. These high-visibility areas are also ideal for admiring the amazing colours.
Other information online
Note: if you do a web search for crotons, much of the information you'll find refers to cool climates where they are kept as pot plants. Some of the cultivars referred to in international links might not be available in Australia, or might be sold under different names.
) At "Grow Me Instead" (an Australian website informing gardeners about safer alternatives to invasive ornamentals)
Harry P. Leu Gardens, Orlando, Florida (PDF)
Colorado State University
Possible misspellings: codieum, codiaum, codium, croaton
Queensland Poisons Information Centre