Right now I'm beta testing my app and requiring all interested users to email me directly for access. This sets up a communication channel for feedback. They're

Right now I'm beta testing my app and requiring all interested users to email me directly for access. This sets up a communication channel for feedback. They're more likely to send feedback because there's already a conversation in their inbox, and it's easy for me to check in and see how things are going. I plan on keeping it this way for quite some time, until it becomes absolutely impossible to scale further. I usually just ask "How are you using it?", or "Is there anything that didn't work like you expected it to?"