It's not acceptable for women to wear short shorts on the street and a longyi (traditional sarong) or long skirt is needed when entering pagodas and temples. Visitors are also required to remove shoes and socks. There’s no need to hike up your skirt or sarong while you're walking around the temples; it's okay if it drags a bit on the ground.
Business-card customs here are the same as elsewhere in Asia. If you plan on doing business in Myanmar, have cards printed up with English on one side, Burmese on the other. Business cards are exchanged with two hands.
Be respectful of language difficulties. Although English is widely spoken, try and speak slowly and enunciate when talking to locals, especially over the phone.