Things to consider: -The leadership, is it someone you want to work for and if multiple people do they get along with one another. -How much you believe in the idea, if you're not all to crazy about the ideas you come across in your job search then you may be better off applying for a more stable company. -Their funding, if they are funded that makes it easier for them to pay you continuously. -Their offer to you, the questions that matter with this is how much of both cash and equity will you be receiving, how much you believe in the idea and what you believe that stock will be worth later on, and what your base salary is. If you're not head over heals in love with the idea and whole heartedly believe it's the next big thing with the original founder already having done market research/testing to prove that customers want the product then don't be the technical cofounder of a 'potentially' successful company.