For social occasions, arrive a half-hour later than the stated time. Contrary to the U.S., only the arrival time is noted on invitations. It may be insulting to your guest to list a departure time. It is important to realize that Mexicans have less control over their business environment. Most offices are open from 9 a.m. to 6 p.m., Monday to Friday.
Shorts are a no-no.
Not even for a picnic. If you are invited to a picnic or a tour of the country side, dress casually, but elegantly. Polo style shirts, a sweater and sporty slacks would do. Business meals are the time to get to know each other, conversation may wander through many different topics. Breakfasts are also the preferred choice to meet, get to know, and exchange information over the potential business deal.