Before you seek external finance, you need to work out what is realistic in terms of amount, the timescale and the factors that will affect these calculations. Backers expect you to arrive at the sum you seek through careful planning and rigorous research. Fundamentally, they want to know what it is for, how long it will last and when you will provide returns.
It is important to be realistic for the stage of development your business is at. For most companies funding levels tend to rise incrementally from small amounts of debt, to more sophisticated facilities (such as invoice finance and leasing), to angel, venture capital and public market funding. Think about: