Begin by closing the cards that have been opened recently. The older the card is the more it helps you credit (over 3 years). Then close the cards that have low limits. Then in a few months check your credit and make sure that they are reported closed BY CONSUMER.
References :

After you cancel all the cards, take a big pair of scissors and cut them into little bits. Finally, add some lighter fluid to them and set them on fire and send them back to the hell from which they came.

Credit cards are no good and if you can avoid any debt with them you will be well on your way to having money when you are older. There is no reason to need credit cards with proper money management
References :
http://www.daveramsey.com

What I did was place ALL of my cards on the table. First, I chose two major credit cards to keep (i.e. Visa, AMEX). I chose one that I used regularly and one that I didn't use. Then I picked out the ones that I had NEVER used (like Pier 1, etc.) and I called to cancel them. I basically kept one gas card and 3 department store cards, along with the 2 major cards. This was the best thing that I could ever have done. It didn't hurt my credit at all and within a couple of years of doing this, I bought a new car and then my first house.
References :
Experience

Your score will be affected, depending on how high your credit score is and how many other credit reference are on your report besides credit cards. If your credit score is very high and you have an extensive credit history with lots of accounts, then it should be okay to close 2 or 3 accounts. If you are only concerned about the account numbers being stolen, you can call the credit card co. and ask your cards to be flagged so that they can not be used without showing ID. That will make it more difficult for them to be used fraudulently.
References :
Mortgage Loan Officer with extensive training in credit scoring