Research shows that private investors are crucial in the early stage of investments. Venture Capitalists often only invest in start-ups which have obtained an early stage investment. But how do private investors make their decision in investing in early stage start-up? In this report, I act as a Co-investor in the Cambridge early-stage investment Syndicate Room platform and will analyse my decision-making process to invest in three real investment cases. I show how to approach an investment decision, and the tools and techniques you use to guide your analysis and decision making. In this investment cases, my primary goal is to maximise your ROI over a period of five years. I will make an Enterprise Investment Scheme (EIS) investment of £100,000 in business three early stage investment opportunities: TC Biopharm, Mayku, Digital Therapeutics. In this report, I will first outlay the assessment criteria, second evaluate the proposals in terms of the criteria and show my primary concerns, analyse what further data and information is needed to make a proper decision and third finalise my investment decision in a recommendation.