The official information:
Quote Quoting Serving The Notice
The clerk will assist you with forms and general information about the process. The clerk is not allowed to give legal advice. Service of the claim form can be accomplished by any of the following:

  1. The Sheriff's Office;
  2. A process server;
  3. Any person of legal age (18) who is not connected with the case either as a witness or as a party; or
  4. By mailing the copies to the defendant by registered or certified mail with a return receipt requested.

The Notice of Small Claim must be served on the defendant not less than ten (10) days before the first hearing. A return of service, or mail return receipt bearing the defendant's signature, must be filed at or before the time of the first hearing. You cannot personally serve the claim. See RCW Chapters 4.28 and 12.40, and CRLJ 5 for more detailed information.
It generally makes little sense to sue a guarantor without suing the person principally liable for the debt, and whether or not it would make sense to do so will depend on the facts of the case and the terms of the contract.

If the claim is so small or the chances of recovery so slight that it's not worth paying a process server in anticipation of recovering those costs at the successful conclusion of your lawsuit, you need to consider whether it's worth suing as opposed to using other methods of collection.