There are no hard-and-fast rules that indicate the "right amount" to tip a person. The tip should depend on the quality of service that you have received. There are a few general tipping guidelines that you can keep in mind, but these are just suggestions. You should never over-tip for bad service or under-tip a quality worker.
Tip your waiter around 16 percent of the total bill when you are dining out. If the service is exceptional, give the waiter 20 or 25 percent of the total bill amount as a tip. If you are not pleased with the service, tip just 10 percent and inform the manager of your issues.
Tip bartenders and wine waiters $1 per drink and around 15 percent of the total bar bill. Again, you may want to tip a little more for great service or a little less if you've been forced to wait for your drinks.
Tip hotel employees based on the service. Give valet parking attendants a few dollars when you arrive and a few dollars when you leave. If you want your car parked in a certain area, give the attendant a bigger tip when you ask for the service. Tip the bellhops $1 or $2 a bag for bringing your bags to your room. Leave $2 or $3 per night for the maids.
Give taxi drivers 10 to 20 percent of the total fare as a tip. This amount, however, can vary dramatically. If the driver is rude, drives like a maniac and drags out the fare to make extra money off of you, go as low as 5 percent of the fare and contact the driver's company.