Came across this great slide deck. This is precisely what you need to do to validate your idea.
Never take decisions with your intuition. Eg. “I feel people will buy this product.”, “Ye chal jayega yar! (this will surely work!)”. As Paul Graham says:
“It’s like skiing for the first time, you first instinct, when you ski, will be wrong.” – do what your head says, not what you feel.
Use this ‘scientific’ process to validate your idea: