Initially, avoid new issues, especially those from obscure countries that most people haven't heard of (that also applies to the Royal Mint; even they are now far too commercial). To start with buy what you like the look of, i.e. a particular monarch or a particular denomination, or simply everything you like the look of. Get some books in order to learn as much as you can (see links above to my books on Amazon). And, as with gambling, only spend what you can afford to loose just in case and until you develop an eye. It is possible to pick up good things on ebay but 90% of what is offered is overgraded, overpriced rubbish being offered by private sellers that probably know less about the thing they are selling that you do! I have long since given up looking on ebay as trawling through the tosh is too time consuming.