Using the wrong enclosure style
Ivory Ornamentals are arboreal, so spending time above the substrate, webbing around cork and using an elevated retreat are all normal for Poecilotheria subfusca. Build the enclosure around that lifestyle instead of using the same shape for every tarantula.
For Poecilotheria subfusca, adult size is about 14–17 cm (5.5–6.75 in), but enclosure size should still follow the spider's current size. A sling does not benefit from being placed straight into a large adult setup.
Getting moisture wrong
For Ivory Ornamentals, maintain moderate moisture with excellent ventilation. Avoid warm stagnant conditions. The mistake is usually treating the whole enclosure as either permanently wet or permanently dry instead of watching how the substrate actually behaves.
Keep fresh water available to Poecilotheria subfusca. Persistent condensation, a stale smell or wet substrate that never dries are reasons to reduce water or improve airflow.
Overfeeding or chasing a schedule
Feed Ivory Ornamentals according to size, appetite and abdomen, not because a calendar says food is due. Poecilotheria subfusca can refuse meals for normal reasons, especially around premoult.
Do not keep adding prey when an Ivory Ornamental is already very well fed. Remove ignored live feeders and offer food again later.
Disturbing premoult or moulting
When Poecilotheria subfusca shows premoult signs, remove live prey and leave the spider alone. A closed retreat is not an invitation to open it and check what is happening.
After a moult, wait until an Ivory Ornamental has hardened and the fangs have darkened before feeding. Larger spiders usually need longer than tiny slings.
Making maintenance too difficult
A good Poecilotheria subfusca enclosure lets you refill water and remove food remains without dismantling the main retreat. If every job requires moving cork, digging into substrate or working directly over the spider, change the layout.
Handling is not part of routine care for Ivory Ornamentals. Use long tools when useful and have a catch cup ready for rehousing.
Changing too much at once
Once an Ivory Ornamental has settled, avoid repeatedly rearranging the enclosure for appearance. Stable housing usually matters more to Poecilotheria subfusca than a constantly changing display.
If something needs correcting, change one clear husbandry problem at a time. That makes it easier to see whether Poecilotheria subfusca settles, feeds and uses the enclosure normally afterward.