How you guys validate if your business idea has potential or not?

The potential is based on your capacity to build a product that offers a solution that is being sought out by the public, or if you are more ambitious, could create a trend within a given community. Depending on what industry/field you are on, you will have to be well-informed. You can read journals, forums, and online research (topics, comments on "x" products, issues within the field, etc). If possible, you can contact experts from different offices, and ask them to pinpoint the pains clients/consumers face the most. It really comes down to your involvement, dedication, and passion in the industry you are in. You will end up with a list of data that will lead you to think through what's going wrong for most people, why, and how it could be avoided by offering a platform, and tools that help solve those issues. Then when you got the concept of the product (illustrations, etc.), introduce it back to those experts or the audience that you previously consulted on the different websites. if it has an educative purpose, it could be school, etc. It depends on the nature of the product. If you get enough positive responses, then it's pretty much validated. Just don't lock yourself into the created concept, keep iterating until you get something out of it. There is no magical formula, keep trying!