Tipping can be a sensitive subject, especially when doing business or traveling to a different country for the first time. In the US, 15% tip is considered normal for standard service, while in nicer restaurants people usually pay upwards of 20%. In Europe, many restaurants include a service charge, so tipping depends on the country and the local customs.
In Mexico, the rules are a bit more straightforward. A standard 10% tip is customary in most of Mexico, while in Mexico City most people leave a 15% standard tip due to the higher cost of living. If service is excellent or you have a larger party, bump the 10% up to 15% and the 15% up to 20% and you should never have a problem. It is important to note that many restaurants have credit card terminals that they bring to your table if you are paying via credit card and they give you the option of adding a percentage tip by simply pressing a number.