I work with a lot of startups as an advisor or thru 500S. Figure out what the biggest value offering for your idea is, create the simplest product that only achieves that big value and nothing else (if this means you don't write code, then great). Get out into the real world and start actually charging people for that service.
Example is Instacart (3 hours or less grocery delivery on demand) when they were starting out (I imagine in a similar stage as you right now), went around shopping groceries and delivering it and charging customers via Square.
Most importantly, the reason you want to do this is to find out or realize that either there are a meaningful amount of people who will definitely pay for your service at which point you develop on custdev and product dev further or there aren't enough and you drop and move on.
Assuming you have several ideas, and you are trying to figure out which one among them to work on, I'd suggest:
1.Try to sketch the business model for the startup idea (referring to Business Model Generation - Canvas)
2.Get good at doing quick and dirty market sizing of opportunities
3.Check if you are passionate enough about the idea to potentially spend the next 5-8 years of your life in making it successful
Based on a collective evaluation of the above three, you might be able to zero in on an idea to investigate further (e.g. building a prototype, customer development, etc.)
Whether or not a business works comes down to two things: (1) are there customers who want the value you provide and (2) is the amount they are willing to pay for that value more than the cost of you providing it?
This hasn't changed in the history of business. What has changed is how easy it is for you to test these two things.
Fear of "failure" often restricts us to judging whether an opportunity will work out in our heads. This is silly. The world is our laboratory.
So, the answer: find a way to develop the idea into the cheapest, easiest possible test to determine whether this is the case. Then go out there and do it. If it fails, great. If it succeeds, even greater. The goal is to use the market to determine whether you have a real business idea on your hands, or just some fantasy you've made up.