Well there are no best ways to handle rejection, infact rejection is bound to happen in business, when you just starting your business it's mostly the first thing you get from people especially friend and family because you haven't really shown them what you worth or capable of doing, there is a saying that a prophet is never valued in his area. If there is rejection the best way to deal with it is to move on and work more on how to improve on what caused that rejection so that the next batch of people will not also reject you, build your business better and you will see that when things start going well with your business the people that rejected you then will come back.