The rule
Attorneys may not represent parties at a California small claims hearing. Both sides appear themselves. You may consult an attorney beforehand, and many will review a case briefly for a modest fee.
This is deliberate: the forum exists to be usable without counsel, and the procedure is simplified accordingly.
What wins these cases
Organisation. A judge hearing thirty matters in a morning has a few minutes for yours. A single chronological folder with a one-page summary on top, one copy for the court and one for the other side, is worth more than any argument.
Evidence beats characterisation. Photographs, receipts, dated messages and written communications — in that order.
Where self-represented parties actually lose
Rarely on the merits. Usually on procedure: suing the wrong entity, defective service, missing the limit, or arriving without the document that proves the central fact.
Name the right defendant
A business's trading name is often not its legal name. Suing “Joe's Auto” when the entity is a corporation can produce a judgment you cannot enforce. Check the registered name before you file.