it depends, u can keep 1 card for all purposes or multiple cards , each for a different purpose. these days for online usage u can create virtual cc's created from your actual credit card. major banks like icici and hdfc have this facility, not sure of others.
also, all banks have a call in zero responsibility option. if u loose ur cc or ur wallet gets flicked , the bank will take care of any illegal transactions that happen on the card 'after' you have reported the loss of the credit card. so as long as u report it on time, its ok. I lost my cc last year and the banks customer service was so fast, they dug out my card based on other searches, without me even telling them the number and the card was locked in exactly 2 mins on call.
if u are getting a high value credit card, dont say no to it , take it and keep it at home if u dont want to lug it around. its extremely usefull in emergency situations like urgent medical emergency's.
keep a track on ur expenses.
keep a limit of how much u can spend on the card.
for me if im too broke to buy something i would buy it on the cc, KNOWING the fact that i will have cash in hand to pay it off in the next cycle before it starts getting on interest.
other benefit is conversion to EMI for large purchases. ( i remember buying my desktop on EMI option and paying a small sum of 1.4k each month) for many its an easier task to pay 1.4k each month then shell out an entire chunk in one go.
last but not the least, it doesnt matter how much of these u have, its how u use it, self control over the counter - and swipe resistance is all you need.