Using placeholders on input elements

I have a number of forms where users must enter phone numbers, credit card numbers, amounts, e-mail addresses and I am using placeholders for these fields in hope to guide the user on what to type in and how. Because I get users who will type in www.yahoo.com for their e-mail or "$1,150 US" for amount or who knows whatever else anything except a phone number for their phone number.

So, after I've added those placeholders my tech support gets hammered with calls that the web apps are not working, that they are trying to type in their card number but they can't because there is already a card number there and they can't delete it, and OMG if I enter my card number will it show up for someone else?!

So I guess I am looking for suggestions as to how I should make them placeholders appear less like "input text" (that can't even be deleted)...would appreciate any ideas!