For testing with our own users, I created a workflow combining Chatra, Calendly, Skype and Amazon Business (to send out vouchers to our users after the tests).
INVEST in good User stories
*I*ndependent (of others stories)
*N*egotiable (not a contract)
*V*aluable (What is the business value)
*E*stimable (at least to a certain degree)
*S*mall (should fit in an interaction)
*T*estable (acceptance criteria)