Research is definitely the key to finding rare coins.
A good book or guide about Coins is a great place to start because you need to know about rare coins before you can spot one! You can visit Coin Fairs and meet up with specialist Coin Dealers.
This is a really easy starting point because you will have the advantage of being able to speak with a few dealers all in one place.
This naturally gives you a feel for things and it is great to be able to speak to a real live person and learn from them.
You can also decide if you wish to do business with them now and in the future.
The newcomer to Coin Collecting might be attracted to purchasing coins via mail order but this has several disadvantages, not least because it is not possible to view the coins prior to purchase.
This avenue might be best avoided until a great deal more experience and knowledge has been acquired.
A Coin Collectors' Club or Society can be a superb resource.
Apart from finding out which brokers are good to deal with you will also learn how individual collections were built up.
Ideas on finding coins will follow as a result.
A specialist Coin Shop is a very good place to find rarities.
Although you will have to pay the market price and will be unlikely to make a quick profit, you will have the confidence that you are dealing with an expert in the field who probably wants to maintain a good relationship with you and good reputation generally.
They are likely to give you good advice as a result.
You might come across coin dealers at more general fairs but this will be less helpful as they are likely to be the only sellers there and might not be a quality dealer, so take care.
You can buy a coin direct from another Coin Collector but, again, you are taking all of the risk.
Using a Specialist Coin Shop will be more expensive, no doubt, but you have much more assurance that you will be buying wisely.
The key to all of this is to find a really good book or guide about Coin Collecting that will steer you in the right direction.