In most business settings nowadays, it’s normal for everyone to call colleagues by their first names. When emailing someone for the first time, though, it’s helpful to address them more formally. The standard in English language settings is [Title] [Family name]. There’s a few things to know here.

• In some countries, the family name is written before the given name, but in English-speaking countries the order is [Given name] [Family name]. So e.g. Prof. Hao Zhang instead of Zhang Hao.
• There are only a few titles that are used in (most) professional settings: Prof, Dr., Ms., and Mr. (There are lots of other titles but you’re unlikely to encounter them in the kinds of workplaces you’ll be in.)
• In social settings, some women use titles that indicate their marital status–Miss and Mrs.–but in professional settings you should use Ms. unless you know for a fact that an individual woman prefers Miss or Mrs., bearing in mind that in her social life she may be called something different than in her professional life: someone who goes by Mrs. Smith at home could be Dr. Chen at work.
• Choose the highest status title that someone is entitled to. Here’s a flowchart.

(You notice that the gender option refers to how they present in the world, rather than anatomy. The latter is none of your business in a professional setting. For people without professional titles, some gender-neutral options have been proposed, but it will be a while before they catch on.)