If you are starting out, don't go all out at first. Build up your collection gradually. Since CM's can't deny a trade, I recommend trading with them exclusively first until you are able to know more about what's hot and such. Should you start trading with non-CM's, please note that some traders ("Sharks") love to take advantage of new traders. They will talk you in to trading an LE pin for a common open stock or "rack" pin. However, rest assured that these unsavory types are not welcome at both the Contemporary and Polynesian meets.
And most importantly, have fun!!!