Having a mentor is very important for an entrepreneur. Most people choose the mentors who are related to them through alumni or work place relationships. The other options which I suggest is to choose mentor from the technology or business area that one's business is in. It can be a vertical expertise or a horizontal expertise.
A mentor can be your advisor or a board member who can help you out in the business development or getting investment to your company. A mentor can be a strategist to your company to chart out a business strategy for you to execute. Having constant interaction with mentor helps the mentee to align the strategy as per expectations.
Most of the time, an entrepreneur has a fear of failure. Failure comes out of personal financial situation and investment that he can afford investing in the company. Having planned one's financial situation, an entrepreneur can try to get his business up and running. A failure need not put him down but help him to create a new business in the right way. Practically speaking every entrepreneur goes through a series of sprints in the business execution.
Entrepreneurship journey is most of the time lonely and there is a point of shift from struggle to success. It is great if you can have cofounder who can be a partner or investor in your journey to share the struggle and success. Getting a right team, cofounders who have a blend of technology and management skills helps. The areas of sales, business development, engineering and recruiting are the key areas cofounders can help.