I've been working on https://TripFate.com for over a year now, and it has been a very exciting experience so far. The response during the year long beta has been overwhelming, especially considering that this is the first product that I've ever built - thank you! I learnt several lessons along the way, which I'd love to share with the community below:
Be ready to scale quickly: I understand the importance of building a lean MVP as fast as possible, but you need to build and architect your product for scalability from the ground-up - you could have an explosive growth in a matter of hours! I made the mistake of ignoring this aspect, and had to spend well over a month on fixing my mistakes.
Make sure customers have multiple ways to contact you and personalize your responses: This is super obvious, but I think it's a really important point. I've received so many amazing messages from beta testers and customers who've been part of the journey. Needless to say, also make sure you reply to each of those threads as quickly as possible and try to personalize each response. It can be overwhelming at times, but it's totally worth it!
Have a clear vision for your product: It's very easy to lose focus and prioritize the wrong features. especially when you start receiving emails from users asking for specific capabilities - do listen to them, but make sure enough users ask for the same thing before going out of your way to implement the changes. My rule so far has been that if a 100+ users ask for a specific feature, I prioritize it.
Try not to get demotivated - you WILL get demotivated as part of your journey. Be it because of some harsh comment on the internet, or some negative feedback, or users abandoning your product. It's okay. You will also have days when you don't want to work your project - again, that's okay, but always try to focus on why you wanted to start the project in the first place and/or how it made you feel when you got your first positive response.
Remember, it's a marathon not a sprint.
Good luck! :)