The first step should be sending a formal, firm, but at the same time courteous letter requesting a payment to be made within a limited amount of time. You can write that letter yourself, or - if you believe that your former employer will be more likely to take your request more seriously if the letter comes from a lawyer - you can hire an attorney for that limited purpose of writing a letter, which shouldn't cost very much.
If the employer refuses to pay your final wages or ignores you letter, your next step should be filing a claim for unpaid wages with DLSE. The DLSE website is very informative and contains all the necessary information regarding regarding how to file a wage claim in California. The filing is free and a relatively simple process.
Most employers who owe a small amount to an employee will much prefer paying it shortly after they are notified of this filing by the Department of Labor, because even their initial legal fees to their lawyers for defending that claim will likely exceed the small amount they owe you, except in those cases where the employer dislikes you so much that they are willing to keep paying to fight you just for the sake of fighting.