How to best evaluate a company with negative earnings? What metrics do we look out for?

I would assume you are looking at a company which is still cashflow negative but growing at double digits and eventually will be profitable.

Isaac has brought up plenty of possible metrics you could use. Personally it depends on the industry the company is in- though i am guessing the sector would most likely be tech or pharma related.

Tech wise- look at the business model of the company and its competitors in the industry. Focus on the metrics investors are largely concerned with. look at the lifetime value (ltv) its users/customers, estimated years till the business turns profitable, its top line and bottom line scalability and offerings. Benchmarking will be tricky- usually it will be hard to find very comparable companies especially since its probably working with some unique business model or product innovation. But following buffet and fisher's teachings- it should be a screaming buy for you to decide to invest in it.

First question to ask is if the company has negative earnings, do you still want to put your money in a company that is not doing well?

Second question is since the earnings is negative, do you think it will become positive in the future? If you are not sure about it, then you shouldn't waste time on valuing this company