This post is my opinion and for informational purposes only, and should not be considered professional insurance advice. These statements are based on my experience with US-based insurance policies.

Specific advice would be tailored to the line of coverage (homeowner's, auto, professional insurance, etc.), but here are some general points.

1. Understand your exposures. Figure out what you stand to loose in the event of a loss. This could be the maximum value of property that could be destroyed, or the maximum probable loss for a liability claim. If you don't know what you're covering, then what is your insurance for? Know what is unusual about your situation. Do you have expensive jewelry, furs, or collectibles in your home? They may need additional property coverage. Do you have a pool or a trampoline? This could increase your liability exposure. Is your car worth more than blue book because it's classic or has after-market parts? You get the idea. Also, consider what you can pay out of pocket when a loss occurs in the form of a deductible. A higher deductible will lower your premium, but may make a loss overly expensive for you.

2. Tell you agent or broker EVERYTHING. This person's job is to find coverage to suit your needs, but (s)he can't do that without a full understanding of your situation. If you're worried that something might make it hard to get insurance, you may be right, but it will be even worse if you lied or withheld information on the application. Failure to disclose everything could lead to the nightmare scenario of paying premiums for years, then having your claim denied because of your omissions. Talk about things like the wood-fired boiler that heats your home, or the creek running through the back of your property that rises when it rains hard, etc.

3. Find a good insurer. For things like service, you'll want to get word of mouth recommendations from friends or colleagues. Financial strength is very important, since your policy's no good if the insurer goes under. The industry standard is AM Best's reports. Go to ambest.com and search for your potential insurer, then use the letter/number combination to decide for yourself the strength (the letter) and size (the number) of insurer you want. With my job, our minimum is A- VII.

4. Read your policy, especially the declarations page and endorsements. For most individual-based policies, the bulk of the document is a form, which is important, but general. The declarations page will list what the covered property or liability is, as well as the insured (that's you), the insurer, the policy term, and any unusual terms. Endorsements can add coverage the standard policy excludes, add an additional insured or loss payee (you may need lenders to be a loss payee), or otherwise amend the policy. The form document will have coverages and exclusions; understand these. Remember that trampoline? It will invalidate some homeowner's policies. The form document is long, but take the time to at least skim it. Ask your agent/broker about anything that doesn't sound right.

5. Pay on time, always. Your policy can be cancelled for nonpayment of premium. While there are notification periods, you don't want to deal with a claim when you haven't paid your premium.

6. Ok, the bad thing has happened. Call your insurance company as soon as reasonably possible. Insurers can have many different procedures, and failure to report a claim on time, have their company adjuster visit the property/site of loss, or otherwise provide guidance can put your claim at risk. I've seen property insurance claims denied because a homeowner repaired a water-damaged wall before the adjuster could see the damage. Since the insurer didn't see the wall, they had no way of knowing that the property owner didn't just tear out old drywall and try to make a claim. If it's a liability issue, like a car accident, never admit fault without talking to your insurer. Also, always document.

In short, always communicate clearly with your insurer, and always know what is expected of you, and what you can expect, according to your policy. I guess this wasn't "very simple," but I couldn't find anything worth cutting. I'll try to answer other questions that you might have.