If you are startup and making a product, I advise you to follow the MVP. MVP stands for Minimal Viable Product. An MVP has least fancy features but solves the core problem for which it was designed. So, I would recommend few suggestions:
Identify the core problem that the customers are facing in existing system.
Build the list of features that are required to solve that problem.
Start making the product with those features only. Avoid any suggestions on how this product can be better in this phase as there is hell lot of time to make a better product. Always keep in mind you are not making the perfect product, but you making a workable product.
Allocate the time and deadline for completion of MVP. If something is dragging the timeline, you can leave that feature from first release. Time is very important for MVP as somebody would also be working on the same idea somewhere in the world. So, if you missed to launch it on time, chances are there that the other guy may capture the market already.
After the MVP is launched, make list of priority two features. Do not try to include hundreds of features in your product. Just keep your product lean. if you try to include every feature that you can think of in your product, you may end up with a fatty product which is fine for 1-2 customers but other are afraid to operate this ‘complex product’.
Ask for feedback on your product from your customers. You may make the short surveys for it and then request your customers to fill it. Do not start working on the feedback of customers immediately. Always keep recording the surveys and only implement a feature if you have heard id from 100 customer (or a large number) of customer.