I am starting a new Computer Repair and Maintainance business.

What would I need to do to prepare for this?

That is a loaded question. Some more info would be a start. Where are you located? Any experience? Mobile or fix location? Competition---in your market.

What ever you need to open any business. Liscense Tax ID etc Business plan.

That's a start. Please give more info for more and better advice.

Your question is too broad... there are many things you need to do, but what in particular do you need to know?