Do you get better hotel rates by not making reservations?

How much should I tip hotel staff for making museum reservations for me in Florence, Italy? when making hotel reservations do you have to have a major credit card? are making hotel reservations with your credit card number safe? ... I work in a hotel and the key is to be VERY PLEASANT. For someone who is nice and friendly we may give a great price and include free breakfast, but someone who has an attitude and is willing to book an expensive suite we may say we're full ...