In countries where demand is high, it is often fine to have a bachelor's degree in almost any field. Getting a teaching position at a foreign university is the hardest, as some sort of EFL degree is often expected. Middle and high schools have more lax requirements, but the English abilities of your students are usually lower. Many countries also have private language schools that cater to students preparing for an exam, or for business workers who need to learn English to stay competitive in the global market. Private schools have the most flexible schedules and the most lenient prerequisites for teachers, but have developed a reputation for overworking their teachers in many countries (it's not uncommon to teach 30 hours per week in many Asian language schools). Typical teaching requirements are about 16 class hours per week in universities or middle schools.