I often faced this at work as a UX Designer. We often have to come up with new software, new processes, new tools, new architecture and justify our reasoning behind it. Two things that have helped me are 1. timing and 2. a daily commitment to researching/learning 1. I have learned from past mistakes that timing is everything in a conversation. Take your time, listen to everyone's points, list everything you want to say about your argument in your head, count to three and present it. Tell them why you think that way, why it would be good for the business and how you could accomplish it. 2. I think this applies to any field, any conversation but committing yourself to learning and researching things outside your normal world has been the way I have advanced my career. I am able to recall strategies that other companies are using just by reading the tech section of google news. I am able to present logical arguments of the best way to present something to a customer based on psychology studies I have looked up. I have been able to estimate effort and time for projects based on looking up articles on technical implementation. Be sure to remember the sources of where you got your information, who/what company is using it and why you think it would be beneficial. Keep on going and always learning!

Definitely spend time with your users. I would observe them doing their daily tasks (around the product you intend to develop). I would first just observe and then later follow up with questions on a second round of observations. You are going to want to understand their goals, their hopes, their fears, their frustrations, and their moments of using their tools before their process, during their process and after their process. Usually those unspoken moments will give you a lot insight. The hard part is asking those questions in the moment and how get what you need answers by those potential users. A UX expert will understand how to pull out the information you need (which I train both UX employees and Product owners in gathering insights). I would be happy to answers any of your questions in this research gathering stage and what to do with that information going forward.

Based on my experience working on apps in the start up realm is to get your first user in the door. How you appeal to them depends on which market you are in... Which, I would be happy to set up a call about. To give you a broad idea you can go several routes - discount, word of mouth, paid. Depending on your app, gamification will also have to be research and validated through design. As a UX/UI designer, we have tons of background of how to best get the user hooked on their brand. To put it simply there needs to be some motivation and then a reward system. Hope this helps!