Private medical insurance (PMI) covers planned consultations, treatments and operations - be it hips, cataracts, ears and sometimes mental health too. It's a lifestyle choice. It ain't cheap. A healthy 25-year-old could scrape as low as £10/mth for a basic policy, but by 40 that'll easily double or more - and most pay far, far more.  

If you're considering it, or want to measure how your current policy stacks up, our full Cheap PMI guide will help, but here are key need-to-knows...

1) Start by doing a quick comparison - through special MSE Blagged links for an up to £100 discount. While big-name comparison sites seem to offer PMI, actually they're mostly just 'white labels' of two specialist comparisons (ie, while they may be branded Gocomparethesupermarket, under the bonnet the engine providing the comparison is one of these two).

So we've gone direct to the specialists, and blagged extra discounts. The two sites have 10 policies in common - the others differ - yet as they can also have their own special prices (as long as not more than direct) do check both if time.

Annoyance alert: Both want you to put your phone number in, and may try to contact you by phone or email to discuss a quote. There's no way to opt out. It would of course be terrible if you accidentally put in a non-working phone number.

2) Under 40, healthy and exercise a lot? Factor in Vitality's PMI perks, eg, £27 Apple Watch 7 or 50% off gyms. Vitality healthcare is included in BOTH comparisons (view it via the comparisons above to ensure you get our blagged cashback / vouchers). The perks offered are so strong, they can skew what's best value, especially for younger and healthier applicants who'll therefore have lower quote levels.

The standout perk is an Apple Watch 7 (normal cost £369) which Vitality PMI members can get by paying £27 upfront, then the rest over three years. Monthly repayments depend on the 'Activity Points' you earn. At the top level, eg, 10,000-13,000ish daily steps, you pay nowt more - equivalent to a £9.50/mth gain. Even at lesser activity there's a decent saving (you do need to pass a credit check).

Therefore if you'll stick with it for three years, do the exercise, and would've bought a watch anyway, factor this in as a cost reduction to see how it stacks up against the other comparison results. It also offers 50% off many Virgin, Nuffield and Pure monthly gym fees and other retail discounts.

Alternatively, Aviva can give 15% off year 2's premiums if you follow its recommended actions to improve your lifestyle, after filling in a questionnaire. For more info on this and others see PMI perks.

3) Thinking of switching? Huge savings are possible, but BE CAREFUL if you've had treatments. As PMI prices have been walked up each year (rising year-after-year so before you know it they're far more than when you started), a comparison can often reveal huge savings. Great, if you've never claimed.

Yet, if you've had treatments on the policy within recent years, and the issue reoccurs within 2-7 years (varies by policy), a new one may exclude that as a pre-existing condition. If that's an issue, you may effectively be locked in to your current provider.

Then the best route is to haggle with your existing provider at renewal seeing if it'll price-match the cheapest found. As Tony tweeted: "@MartinSLewis @MoneySavingExp I saved £1,001 (35%) on a private health insurance renewal quote by haggling."

4) The excess matters. This is the amount you'll pay towards any individual claim or all claims per year (check which one - per year is better, but costs more). It has a huge impact on cost. A £1,000/yr policy with no excess reduces to £720/yr if you set a £500 excess.

So think about at what level you'd claim and whether you're wanting a 'cover everything' policy or only a 'cover big things' policy.

One strategy some consider is to combine a very high excess (£1,000+) policy with self-insuring - where you put cash in top savings to use for basic private treatments but have the ability to claim for expensive treatment.  

5) Pick the right PMI cover. Comparison sites should give an overview, but always do a detailed check of what's covered before signing up. More help in picking a PMI policy, but do check...

- Which hospitals can you use? Bigger choice = bigger cost. So once you home in on a policy, check its hospital list and options.

- What treatments do you want to cover? Options can include improved cover for cancer and mental health. Consider what you'd be happy to use the NHS for.

- Consultant limits. If you have a specific consultant you like to see, if they're not on the approved list they may be part-covered, so you pay the difference, or not covered at all.

- 'Full medical underwriting' (FMU) vs 'moratorium'. With FMU you disclose your medical history at sign-up (possibly via a check-up). Moratorium doesn't need that, but if you claim for a condition within the first 2 (or sometimes more) years, you'll often need to prove you haven't suffered from it before, which can slow things down.

6) The problem with PMI as a staff perk... Getting medical insurance paid for you through your work is usually great. Even if your employer doesn't pay, it can be substantially cheaper than getting a policy yourself. There is a 'but' though...

If you need treatment, claim, and then later decide to leave your employer, will you be able to continue your membership with the healthcare firm on the same terms? If not, you may then be stuck without being able to get a new insurer to cover that pre-existing condition.

7) Can't find what you want or confused? Use a broker. If you're confused or have conditions that make things difficult, get assistance from a member of the snappily titled Association of Medical Insurers and Intermediaries.

These brokers can answer questions about cover, particular insurers' records, rules and more. Most are free to you, because they take commission from insurers if you get a policy. Though, of course, check how and if they'll charge before you get the advice.

8) Claim unfairly rejected? Go to the ombudsman. Picking the right policy is only half the journey - it needs to deliver when you need to claim, too. But it's more difficult to predict how it'll perform.

So it's worth knowing these are regulated policies where you have a legal right to be TREATED FAIRLY. If not, make a formal complaint, and if it still doesn't stack up, you can take it to the free Financial Ombudsman Service to adjudicate.

With a healthcare cash plan, if you shell out for key NHS or private treatments, you then send off the receipt and it gives you the cash back up to an annual limit (the more you pay, the bigger the limit).

Few have heard of these, unless they're a workplace perk, but many should consider them. These can work with PMI or by themselves. Full help in Top healthcare cash plans but let me take you through the key need-to-knows...

1) The core is dental and optical treatments... if you or your family wears contacts/glasses and gets annual dental check-ups, cash plans are likely a winner. With the best policies, if you will max the claim back just on these two categories, you get back more than the policy cost, so owt else is a bonus. For example, with Hive Bronze, one of our top picks for individuals...

... you're quids in.

Other claimable items include £140/yr for dental accidents, £150/yr for therapies (physio, osteo, chiro, acupuncture), £125/yr for consultations & tests (physician/surgeon & PET, CT or MRI scans), £17.50/day for hospital admissions and £100/child for paternity / maternity.

Tot up how much you currently spend on routine appointments, and see how much you'd get back as a rough valuation of whether it'll be worth it.

2) We've analysed plans to help you pick. There are no comparison sites we're aware of, so we've calculated which offer the highest potential value (potential payout compared to cost). So see our top for...

Individuals (from £7/mth) | Couples (from £14/mth) | Families incl children (from £18/mth) | Individuals over 65 (from £7/mth)

If you or your partner are employees, check if either of your employers offers work-based policies. These can be extremely good value - bulk-buying power means firms can negotiate big discounts. And with all policies, always check the terms in detail before signing up.

3) If you WON'T remember to claim, DON'T get a policy. Just because people can claim for the cost of healthcare through a cash plan, doesn't mean they do. You have to fill in a claim form and send receipts each time. If admin fails are part of your DNA, don't bother with cash plans.

Apathetic customers, who don't claim, but have direct debits dripping from their bank accounts, keep plan providers' coffers healthy. Cash plans only have value if you'll make claims.

4) Most don't require a medical for under-65s, though you must declare pre-existing conditions. Most policies will exclude all future claims on any past medical conditions (not routine dental or optical though), but some only exclude specific conditions suffered in the previous 12 months.

Even so, depending on the condition, this doesn't mean you can't head for the cover – past shoulders injuries, for example, wouldn't stop someone claiming for physiotherapy treatment for knees (or toes) injury.

5) Some firms have a 'qualifying period' so you can't usually claim for treatment in the first few months. These normally last one to six months (or 10 months for childbirth claims) before you can start to claim anything, to stop people joining and cancelling to cover specific treatments. Their aim is that these are longer-term policies.