I am a new buyer, I want to know if a seller know he/she is doing (If S/he is a pro)

[salelandingguru]

I am totally new to this…I want to develop a game and I have messaged a developer and he seems unsure with the game requirements… please can someone tell me what are the necessary documents, information, requirements I must have to develop a game or what are the correct questions a game developer must ask me so as to be sure he/she knows about the project