Principles:
ASK FOR THE STUDENTS' FEEDBACK!!! e.g. free chapter
Don't create a product until people ask you to
Focus on ppl who already like your product
Give first to gain trust
Build a list
Clean
Simple
Minimise email
Minimise spending
Marketing/advertising too much is a waste - THEY should find YOU
Don't waste time working with sb you don't trust
Do you want to pay with your money or your time

IDEAS:

Online
Udemy online courses for individuals as well as EFL schools
italki video + teaching
YouTube videos

EFL
 e.g. try the course out on their teachers for feedback?
St Giles
IH London and IH abroad
Malvern House
Stafford House

Government
FCO
Embassies

Corporate
Google - Lukasz
Pret
BBC, ITV
ICBC, Bank of China, Spanish banks
impactfactory.com
mayfairchan
SAS - Agnieszka
BCG  - Bella e.g. relocation package

Universities
lecturers
overseas sts
MBA sts e.g. LBS - Olena

Links
Matthew Moreland, House of Speech