Free Traffic Legal Advice

I'm think of buying a s/h Skoda Superb, I've seen one for around £12-13K but its a private sale.

How do I protect myself from scammers or buying a rogue car?

Am I best buying from a dealer?

To expand a wee bit on Andy's admirably concise answer ...

If you buy from a dealer, you have the protection of consumer law, including (if you pay part or all on credit, the ability to claim from the credit provider in any dispute). Depending on the dealer, they may also have a reputation to protect. Possibly even a manufacturer's back-up.

Buying privately, you have none of that. You have no come-back whatsoever, unless the seller actually misrepresents something. There's plenty of advice available  online on what you need to check, but your diligence needs to include as a minimum a credit check (is the car his to sell), MOT and service history, condition (get an expert involved if you aren't one) and a test drive (for which you will probably have to buy insurance). Also, make sure the "private" seller is not in fact a dodgy dealer.

Your choice, but for your sort of money I'd be going to a dealer every time.

there are of course many "dealers" who know all the tricks to con you.
if you buy privately... after checking out the seller and getting a vehicle check you can get a test by someone like the AA. you can also take out a warranty on it.
you won't get statutory Consumer protection.
if you buy from a dealer of any sort. pay all of it or a deposit of over £100 by credit card to get section 75 cover.
even debit card will give you charge back rights if the issue fits the criteria.
 

I'm currently in dispute with a "dealer" in the High Wycombe area who sold me a car that has over 50 faults showing on the autologic box. 3 moT fail items with a clean MoT sheet, he's offered a refund or another car, was coming to collect dud car yesterday and hasn't turned up yet. His warranty is 3 months on engine/gearbox/transmission. Gearbox shows 2 faults as well. Now pretending to be a private seller. Be very ware!

Thank you very much Roy and everyone else who have contributed.