Please feel free to take or leave the following "advice". It's given as a general guide and without knowing what individual circumstances, values, etc. are or even the countries in which you live. It's based on UK insurance practice. I've worked in the insurance profession for all my working life, which is 32 years and I'm a HO Underwriting Manager for an insurer in the City of London.
1. If you shoot professionally (full-time or part-time) it's probably best to insure your gear separately from your home contents / personal possessions. The policy that covers your home buildings and contents (etc) will not, normally, cover equipment used for your business or any liabilities (claims for negligence, injury or damage) made against you for any work you've done. There are lots of adverts in photo mags or just "Google" camera insurance.
2. You will normally be required to insure your equipment for the replacement value "as new". That's not a problem for digital kit but it can be for us filmies. For those items you have where there isn't a "new for old" option, you will need to tell your insurer and get them to agree to an "agreed value" (indemnity) settlement basis of cover. You will then need to set the sum insured on items that can't be replaced as new at a level that is equivalent to what it would cost to buy the same model / same age and same condition.
3. Take photos of all your kit - detailing serial numbers and any distinguishing features. Once you've done this, put a copy in a zipped folder and send it in an email to yourself - just in case you ever need to prove the existence of items and your home / records of your kit have been destroyed. It will be up to you to prove you owned the item in the event of a loss.
4. You will be required to insure ALL of your kit not just the expensive bits / bits you can't do without. Insurers do not appreciate being selected against.
5. Be careful to make sure you know which bits to specify and which will form part of a "general" figure. Often, insurers will require items with an individual value of £1,000 or more to be specifically mentioned on the schedule. The rest will be covered on the basis of "any one item not exceeding.......". But the premium will be based on the total value at risk.
6. Unless you arrange specific cover, you will NOT be covered for "mechanical or electrical breakdown". This cover is only available in the engineering / extended warranty market and often only on new items. Think in terms of the cover you are offered when you buy a new washing machine, TV, etc. Cover you WILL be offered is usually for physical loss and/or damage to the equipment you own.
7. Professionals will pay more than amateurs. More extensive use and higher value kit.
8. Don't ever lie to your insurer. I REGULARLY authorise refusal of claims where my company has been able to prove that a claim isn't completely genuine - i.e. over-inflated values, claiming for items that didn't exist, claims where no damage had occurred or where damage was deliberate. I don't like doing it but neither do I like putting premiums / rates up for those policyholders who play fair as a result of the actions of fraudsters. It's not a victimless crime.
9. There will ALWAYS be exclusions - even though the policies might be called "All Risks". This is to avoid inevitable claims - leaving your gear on a beach when the tide is coming in (reasonable precautions to avopid a loss) or lack of care such as leavng kit in an unattended vehicle. Some insurers will provide this cover subject to an increased excess and/or where the items are in a locked boot (trunk) and the vehicle is locked at all points of entry and the alarm / immobiliser is set.
10. If you use your kit abroad / take it on holiday with you make sure that (a) the policy provides cover for the places you visit and for the duration of your visit(s) and (b) that there isn't a limit to the total value of kit that your policy covers at any one time whilst you are out and about. Watch for restrictions about leaving kit in hotel rooms - a common place for stuff to go missing. If there's no mention, check that cover would apply. If it's not clear, put your kit into the hotel safe when not in use.
11. You get what you pay for. Don't buy sub-standard cover - make sure the cover you have is what you need. It's YOUR responsibility to make sure it's right not the broker's and not the insurer's. Don't leave it until you have a loss to read your policy / schedule, exclusions and conditions. At that point it's too late and you may not get your claim paid.
Sorry that was a bit of an epic but that's just some of the more obvious things to think about. At the end of the day, we always tell people to act as if they don't have insurance cover - even if they do.Insurance is only there to cover things that are outside your control.