Get a free developer instance

• A complete instance with the admin role, configure anything, activate plugins, install Store apps.
• A recent family release (you can usually choose it when requesting), so you can study against the version you will be tested or hired on.
• Enough capacity to practise every core topic: tables, ACLs, flows, scripts, integrations.
• Sample data (the "ITSM" demo data) you can load to have realistic incidents and users to work with.

Treat the PDI as disposable and keep your build portable:

• Do experimental work inside a scoped application or a dedicated update set so it can be exported and re-imported.
• Export update sets / scoped apps as XML to your machine periodically.
• Match the release family to whatever you are studying or targeting for certification.
• Do not store anything you cannot afford to lose only on the PDI.

A good learning path on a fresh PDI: create a custom table, put a few fields and a form on it, add a data policy and a business rule, wire a flow, expose it through a catalog item, and secure it with ACLs. That single exercise touches most of the CSA blueprint.

• Letting the instance hibernate and be reclaimed, losing everything unexported.
• Building in the Global scope so nothing is portable.
• Requesting a release family that does not match your certification target.
• Never loading demo data, so there is nothing realistic to practise against.