Choose where collection is useful
Autumn leaves do not all need removing from the garden. In Britain, start with paths, drains and surfaces where a buildup causes a practical problem. Leave appropriate habitat where it does not interfere with access, and avoid stripping every sheltered corner simply to fill a container.
Keep the material identifiable
Collect leaves separately if your aim is leaf mould. Check for litter and unsuitable material before storage. Choose a method that retains the leaves while allowing the process to develop, and place it where later access will be straightforward.
Plan for a slow process
Leaf mould should not be treated as a quick replacement for every bought growing medium. Label the collection date and keep new material distinguishable from older batches. Check moisture and condition periodically rather than assuming that time alone guarantees the material is ready.
Use the result with a clear purpose
Assess the texture and maturity before using it in the garden. Keep a note of the trees or material collected and any problem encountered. Start with the quantity you can store sensibly; collecting more than you can manage may simply transfer autumn clutter from the path to another corner.