@more2much Make friends in/around your industry. After 20+ years in my line of work, I have gotten to know many, many other business owners, designers, wholesalers and distributors, manufacturers and makers. The old adage of "it's not what you know, it's WHO you know" is very, very true. Being able to get advice and help means you have to have a group of people to go to. I regularly refer customers to other businesses (when I can't provide a product they want), and others do the same for me. You are not automatically enemies with everyone else in your line of work.
Also, it's not a bad idea to set some limits on what you will offer/sell/do. I think new business owners want to latch onto any business they can, which can mean they are stepping outside their comfort zone with products or services they don't understand or like or they are underselling themselves.
DO NOT become a discounter. Be the kind of business that attracts the types of customers you want. In my industry, there are a lot of "discount" stores, and they are literally taking money out of their own pockets. I sell things at full retail and specialize not only in having hard-to-find, exclusive, and high-quality products, but I also provide great customer service, which is very appreciated these days. When you sell things (or services) as cheaply as possible, you are attracting cheap, picky, pain-in-the-butt customers who will leave you the minute they find somewhere they can pay $5 less.
Be prepared for some long hours. Focus on slow and steady growth over time (rather than all at once). If you get in over your head early, you will lose the customers you've gained and make yourself miserable in the process.