1. As far as PCI compliance just use BofA business merchant services and use the clover all in one system. It acts as a POS (not piece of shit, but point of sale) inventory management employee timecard, credit/debit terminal, etc. It also has advanced statistics so you know what's selling, expence reports etc.
2. I recommend taking a few business classes, it will help.
3. Pick a new name, nerd cave will draw customers away. Something simple and catchy
4. Marketing. Plan heavily for a marketing budget. You want ads online (google AdWords) yellow pages, bing, *active* social media accounts, etc. You want everyone within a 50 mile radius that searches for "my computers broken" "the Internet's broken" "computer repair" "computer shop" etc. Shows your website. Keep the website minimal and simple easy to use design. Also you'll want great tracking to know where people go on your site and where they drop off, where they came from, etc. This data will show you what areas of your website need improvement and what marketing stratigies work best for you.
5. Business plan. Create a business plan and get investors. But do more research in your area. Find out how well "The Computer Shop" is doing. People don't like change, keep that in mind. Remember that computer repair is expensive and you don't want to undercut the labor. When you have 50+ regular customers that can't stop clicking ads and installing adware and random ass virii, as well as new customers and sales, if you do your prices to low that you can't afford to hire someone to help with the load, you will fail.
Be prepared for legal expenses such as business license(s), llc, etc. Legalzoom is a good place to start. Also expect to run around city buildings all day -_-
When you think you've done enough research, you better research some more.
Also know what demographic you're going for. Are you going for old computer illiterate grandmas?
But also keep in mind now a days there are a lot of people that know someone that will do computer work for them.
Also be sure that if you are running a legitimate business you will need to work closely with Microsoft and have VLKs it won't be as simple as your buddy asking to install MS Office for $10. No pirated software on a client machine, you will run into some serious legal trouble. MS is fine using their software as "freemium" but when you start profiting off "freemium" they do not take it very lightly.
Try and get as many things on consignment as possible. This will save costs. People that want their products in your store will do consignment so they make money and you make money.
Remember the law of retail is charge double the price of your cost. So if it cost you $20 you charge $40. Also set a labor rate that you want to get paid. Remember that most computer techs get paid $100+/hr for labor and remember if you want to hire someone down the road you best be prepared to not increase the price for your customers.
If you'd like to talk more and want to bounce ideas around let me know.
Started my business back in August. Haven't turned a profit yet :-P sales, yeah I got about $1500 in sales but an investment of about $3000. I still have plenty of product to at least match my initial investment so that's good haha.
I wish I would've gotten some more guidance, I would have started my business much differently. But now its more learn as you go and grow which could put you in a bad spot. That's what happened to the security company im working for. They didn't pay much attention to the details and they grew, then got sued... So do research and don't start up until you have every contingency planned out