I think 2 is the most anyone should really have - 3 is the absolute maximum. One is your primary card that you use all the time, make your day to day purchases on, rack up points/cashback/benefits and you pay off with each statement.
The second card is your backup card which you only charge to once every few months to keep it active. The second card is if you get in to a situation and need the backup - like if your primary card gets turned off by the issuer for some reason - like it's been flagged for fraudulent use and canceled, That happens to everyone at some point - more so now with the internet, identity theft, etc.
If you read the "experts" they will almost universally tell you not to cancel credit cards, even if you don't use them because you'll then have less available credit, this will push up your credit utilization ratio (amount outstanding versus total credit line) and thus effect/reduce your FICO score. My reply to every last one of them is to take a hike! I've been known to curse aloud at the TV or radio when one of them gets on the air and says that to a caller. The fact of the matter, is that you should not adjust your life or spending habits because of this thing called FICO. This entire fixation with it is primarily a result of Suze Orman...and she just happens to have a financial relationship with FICO.
Now, for most Americans, who are up to their eyeballs in debt, maybe their most important thing to consider every waking moment are things like how any decision will effect their FICO score. Personally, I've simply always paid all my bills on time, never maxed out a credit card, etc. - you know, live within your means and pay your obligations. I have some ridiculous FICO score like in the 99th percentile...our real estate agents have always gone ape sh*t when we've purchased our homes because they see the score and say we can qualify for lots more with any lender. Guess they never considered maybe that's why the score is so high in the first place.
In any case, assuming the amount of credit available to you between 2 cards is sufficient and you're able to pay it/them off in entirety each month, that's all you need.
Also - never, never, ever get a store credit card, no matter what kind of in-store promotion they offer you to take it. Not even worth your time filling out the application. Mastercard, Visa, Amex, Discover are all accepted at every place that has their own store branded card.
