You will note that almost all of my coins are certified by either NGC or PCGS, although I do buy a number of "raw" (uncertified) coins and then submit them for certification myself. For the new collector I highly recommend buying certified coins, and from well established dealers or auction houses. I can only recommend NGC, PCGS or ANACS as certification companies, unfortunately there are a bunch of other companies offering these services which knowledgable collectors will be wary of.
I don't recommend buying anything "raw" off ebay, it's a good way to lose a lot of money. Be especially wary when the raw coin comes with a good story, found in my grandpa's attic/inherited from a rich uncle/etc., almost always a sure sign of a fake or heavily misrepresented coin. Many of the older Chinese fakes were pretty obvious, but they have gotten much better in the past few years and have been able to fool even experienced collectors. And the Chinese have even been faking PCGS slabs, and doing a reasonably good job of it.
Take the population numbers with a grain of salt. The NGC and PCGS numbers are pretty good at giving you an idea of scarcity, but keep in mind the great majority of European collectors don't have their collections slabbed. It is useful to compare the numbers graded though to older reference material, such as Peck, ESC or Spink references. If they list a coin as rare or extremely rare, and only 1 or 2 have been graded, then it probably is actually rare.
This is not a comprehensive list of reference material, just the books I use most frequently.
English Copper, Tin and Bronze Coins in the British Museum 1558-1958 by C. Wilson Peck
A must have for collectors of British minor coinage. There are a few specialized references that
cover specific series in more detail, and new discoveries since publication, but overall an excellent
Coins of England, Published by Spink annualy
Any recent edition will do as it is nearly impossible for the price guide to keep up with changes.
The English SIlver Coinage From 1649 by Seaby and Raynor
Long out of print but the numbering system is still widely in use and they list many varities not listed in
The Bronze Coinage of Great Britain by Michael Freeman
Covers bronze from the Victoria and later periods in great detail, lists hundreds of varieties not
covered in Peck.