I think you have a good plan of staying with your "day job" while you build your client base. A lot of small businesses grow by word of mouth. Your "day job" keeps income coming in and gives you a chance to learn about being self employed and get your client base built up. When I first went into business for myself I met a fellow small business owner. They said this to me, "welcome to working for yourself you get to pick your own hours - all 24 of them 7 days a week." You gotta really want to be self employed to make it work cause it is an unbelievable amount of work.
I'm not familiar with your particular industry but in the beginning I was producing the work, marketing and advertising it, selling it, installing it, ordering supplies, storing supplies, keeping track of inventory, shipping, bookkeeping. Then there's outsourcing if you take on a whole job but you only do a couple of the parts, then you have to hire other contractors to do what you don't do. This is just off the top of my head. I'm sure there are things I'm forgetting.
THEN, when you have really busy times that make up for the times you are scraping by you're not going to want to turn down work cause you'll need it. Then you have to think about hiring temporary employees to help get you through. Then it gets even more complicated cause you have to deal with things like payroll and paying workman's compensation insurance and social security deductions. There are also state resale licenses to consider if your business handles things like that. There are also county business licenses. Then there are times when the economy falls through the floor and you have to get creative about the services you provide to draw more customers in and even consider temporarily working for someone else to get you through. Small businesses open and close all the time.
A lot of counties offer small business help through county government programs. I'm not sure if the SBA is still around (small business association). Depending on the type of industry you're in there are often small non-profits that specialize in helping people get started with small businesses. I've used a couple of those to help me with things like accounting and times when I needed legal help, like when people don't pay you for your goods and/or services. I think quite a few community colleges offer adult ed courses for starting a small business and often these are at night and are short term. I think if I had to do it all over again I would start with one of those classes. I learned a lot of it through friends that were small business owners, people who took pity on me, and then trial and error, the trial and error way was a real drag and I wouldn't recommend it.
I would say some of the most important starting points are;
*Know your industry, a lot of successful small business owners come from families that were small business owners and/or they know what they do like they know the back of their hand.
*Understand what kind of market there is in your area for the services that you are wanting to provide. Are there umpteen amount of service providers offering the same services that you want to provide and you're all fighting over customers or is there a real need for the services that you are wanting to provide.
*Figure out what your start-up costs are going to be. Do you need specialized equipment, tools, etc. Can you work out of your own house? Can you use your personal car to get you to and from jobs or do you need a work truck?
*Decide on the best way to market your services. What, where, how, and who.
*Make sure you know what licenses you need to operate a business in your area.
*Find and build a solid client base for when/if you make that break from your day job. These are your loyal customers who will always send more customers your way.
*Last but not least KEEP REALLY ACCURATE BOOKKEEPING RECORDS. It is no fun to be audited as a small business owner and it is even less fun when your records are a mess.
It's financially scarey as hell and there is a ton to learn, plus it is really expensive to get health insurance as a small business owner. So if you have a family and kids this can be risky. If you've made it this far into this post and aren't completely overwhelmed and scared ****less - I would say go for it. If you like variety, being your own boss, can handle the financial ups and downs, and don't mind putting in the hours it can be very personally satisfying and hopefully financially satisfying too.
Good luck.
