The world is no limit
Why teach English only locally when you can teach across the globe ?
Once you master using the English language course books and start teaching, you cannot only offer private English lessons from your home, or go and teach students at their home, or even open your own language school, all of which mean physical students who either come to you or you to them ...BUT ... you can also teach english worldwide via Skype.
As you have probably read elsewhere on this website, the trend of teaching or learning a language via Skype is growing by the day and more English language students worldwide opt to find a native speaker English teacher via Skype, than local non native English speaking language teachers.
So for example, someone in Spain who wishes to learn English may opt to find an English language teacher who is a native speaker, rather than go to the local language school where Spanish natives may be teaching English. And to do this, the student will search for one on the internet, and possibly find one that lives half-way across the globe.
Types of language students who use Skype teachers
The typical language students who will prefer to take English lessons via Skype are usually people who are already out of school or university, and either wish to learn English for the first time, or people who already speak some English but need to improve.
In both cases these students usually need to learn or improve their English because either their job demands it, or they wish to get a better job as they know that if they speak English they have better chances in their working life.
These will usually be people who already work and don't have the time or want to attend a language school after work and prefer to learn English from the comfort of their homes via Skype.
There are literally millions of such potential students world-wide and their numbers are growing by the day.