I am doing the same thing as a wedding planner.
What I have been doing is visiting lots of trade shows to get contacts of caterers, venues and other suppliers. I have also been making appointments with lots of wedding planers pretending that I am planing a wedding to pinch all their techniques and look at their contracts and basically pick their brains as to how they work. This has been really useful!!
My next plan is to actually do a wedding for a client free so that I can get some experience without the worries that they have to give me a fee - means I can be honest that this is my first professional job without them legging it.
You could I imagine do all this stuff to to get you started.
There is a book called 'from acorns....' you can buy on amazon which is brilliant and full of loads of tips about starting your business and how to puttogether your website and lots of really practical stuff.
Good idea to get some basic acounting knowledge experience.
If you go on the websites of most banks they give you a template business plan to assist you in completing for any loans you might need. Is there any specific area of new business that you are wondering about??