If you are filing a claim on a policy you own, read the policy section on the requirements for filing claims and follow them closely.
Documentation is essential in filing a claim, whether it is to your own insurance carrier or if you are making a claim against a third party. Keep copies of all medical bills, invoices for purchase of replacements of damaged or lost property, estimates, and so forth. Check with your insurance agent if you have a loss - don’t assume that it isn’t covered. You may be pleasantly surprised. Set up a file on your claim, and keep copies of all correspondence, notes of who you spoke with and when, their phone number, and so forth.
If you have a small, straightforward claim (typically under $5,000) against a third party, send a letter to the party responsible for the loss. Clearly describe what happened (include the classic “who” “what” “where” “when” and “how”), what your losses were (use the key words “bodily injury” “personal injury” or “property loss or damage” and “negligence” as applicable) including their value, and why you think they are responsible. In general, there has to be negligence on the part of the third party in order for them to be legally responsible for your loss, and it will help your claim if you can articulate in the letter how they were negligent. This specific wording will trigger the respondent’s general liability policy (or other policies), and may help you obtain a quick settlement without your having to involve an attorney.