Before you quit your day job and plow your hard-earned savings into your business idea, you should test what you're working with. This doesn't need to be an arduous or expensive endeavor, and can be done with more creativity than you'd imagine. Additionally, the goal of any test should be to build confidence, not wait on an absolution.
Like any form of testing, metrics matter. Make sure you are clear going into your experiment what good looks like, and what you are hoping to learn. And remember that any experiment you chose to design and carry out should give you the confidence you need to take the next step. This is a soft metric, but it matters. You might learn something contrary to what you were expecting, but if it bolsters your confidence in your idea, it should be taken as a win.
Pitch at a demo day
Hit your local co-working space, search places like Meetup, We Are NY Tech, and 500 Startups and sign yourself up for a pitch day. This will give you good practice refining and articulating your proposition and also give you valuable feedback on your idea. If you commit to doing one a week, you will have a refined pitch in no time.
Tell everyone you know
A lot of entrepreneurs are very protective of what they're creating and refuse to tell anyone what they're building. This secretive mindset means they miss out on a golden opportunity to get feedback from others. By talking to people, often, about what you're up to, you'll learn new perspectives and see holes in your idea that you may not have seen before. You can formalize this process and invite friends and acquaintances to a happy hour, where you ask them to dissect what you're creating. Alternatively, you can hit the pavement and conduct informal man-on-the-street interviews. This down-and-dirty tactic is surprisingly revealing and informative.
Create a landing page
In a matter of minutes, you can create a landing page with an email sign-up sheet that shares your concept and vision. It shouldn't go into painstaking detail, but it should be compelling and clear. Remember, you are trying to captivate people at an emotive level (not just sell a product), so be persuasive and poignant about why you are doing what you are doing. Before you launch your landing page, set a metric on what number you are aiming to hit.
Promote some posts
Start by creating a refined target audience through Facebook filters; you should be filtering by both a combination of demographic (age, sex, location) and psychographic data (like what other brands they like). Create 3-5 Facebook or Instagram ads (or posts) that articulate your proposition in clear and distinct ways, and then promote them to your targeted audience. Once you have served your refined targets these 3-5 separate messages, take stock of what messages resonated the most by tracking click-throughs and engagement.
For any tangible product, create at least two product and packaging mockups and list them on Amazon. Make sure they have distinct looks, and clear propositions that sell your product on different merits. Allow them both to live for the same amount of time and then check in to see which is performing best. Use any feedback you glean through comments and enquiries as a way to tweak your winning prototype.