Read the California probate code will contest provisions -- especially sections 8250-8254 -- to determine whether you have standing and grounds to bring a will contest. Use the California court self-help centers to complete research and to obtain legal forms as well as state probate court rules (see Resources). Familiarize yourself with the local rules and procedures of the probate court in which the will was filed.
Ascertain the time period within which you may file an objection to the will. While this period varies between jurisdictions, It usually runs about two weeks from the date the will is filed with the probate court. Within that time period, prepare and file an objection describing your standing to contest the will, the will provisions you are contesting and the grounds for your objection. The court will set a hearing date and summon all interested parties to a hearing on your objection.
Review any material sent to you by opposing parties. If a party files a demurrer to your objection -- a document arguing that your objection is flawed -- the court may give you time to rewrite your objection. Redraft your papers carefully to meet the objection.
Prepare your case. Assemble documents and witnesses supporting your position. Respond to any proper discovery documents sent to you by opposing parties. Prepare your own requests for information according to local rules and procedures.
Appear at the will contest hearing with all evidence you have amassed and all relevant witnesses. Ask the witnesses questions and present evidence as directed by the court. In California, a will contestant has the burden of convincing the court of most grounds for a will contest.