I know that I could find the answer on Google, but it will take a lot of time to research and understand why and how. I want to open a marketing agency for startups to help increase sales and return on investment. In this case, I need your help with suggestions and a proper guide to follow the steps for building a successful marketing agency. Tell me which key factors I should consider and the best practices in the market to include in my strategy. Also, please provide me with details of how much of a budget I have to set for this. I would appreciate your contribution to this.