It all depends on what you earn and what you (want to) spend. If you're traveling internationally, then you have to account for that too... Some CCs are useless once you go overseas.
Well, before any other transactions, like "buying" credit cards as you said, try to have a research on that bank or institution first. Here are some pointers on how to get a good and trusted credit cards http://www.articlealley.com/article_1006912_19.html