One of the first things to consider is what kind of data you have to work with in your cash flow template Excel spreadsheet. Ideally, you're looking for accurate monthly data including income statement items like revenue and operating expenses and balance sheet items like equipment purchases and cash from financing activities. If you have a longer time frame you can go with quarterly periods, but annual tends to be too long. After all, how can you predict what is going to happen beyond 5 years with any accuracy unless you're valuing an annuity?
Finally, when applying discount factors, where do you intend to get your discount numbers? For a company with existing debt and equity capital you can calculate WACC and use that. For a startup company you need to figure out a risk_adjusted cost of capital that makes sense. Usually this is not just a risk_free rate which only the largest companies in the world have access to. It's probably something higher.