Melissa, it can be overwhelming to think about everything all at once. So, don't do that!
I started my business by working on it part-time for about half a year while I was still employed. That way, I had a business name, mission & website all ready to go.
This article: Take Baby Steps to Owning your Own Business
has some tips on easing into it. The links at the bottom to business action planning articles are definitely a great way to plan out the various steps you'll need to take. There's even a link to my planning form -- I've used it for years in several different businesses.
And, finally, you might find a useful tip or two in my Freelance Writing
As to fear, ignore it. Truly, pretend it's a screaming toddler, step over it and go on about doing your stuff. Fear is supposed to protect us from harm, not keep us from our dreams. Sometimes, fear gets bored & tries to infringe on other territories. There are no vicious tigers who will eat you if you pursue your dreams. There is one who will eat you up if you do not--it's called regret!
Good Luck! By the way, you are in great company-there are so many good writers here who can help you along the way!