First off let me say there is a lot of good information from the previous posts.
A little about myself stated working in this industry in early 80's as a apprentice for a German Car shop after completing the training I work for the shop for a few years.
I started my own shop in1987 specialzing in only German cars at the age of 27 I knew how to work on cars but no idea on running the shop, it was a 5 bay shop on a busy street in a small beach town, the entrance was small and speed on the road made it difficult to enter and exit safely. Also I had to come up with $65k to buy the business, big mistake, never buy a business and if so the customer base in the automotive repair business is of no value, depending on the equipement it's pennies on the dollar at best.
After a few years I had the opportunity to move to a different location about 4 blocks south, The shop was a bit smaller rent was less but the building did not face the street, plus I was sharing the building with other tenants so parking was a issue, Still struggling due to low car count, buying diagnostic equipement and lack of education on running the business and marketing.
In 2000 I moved out of the area and closed the shop, I found a shop in my new town, which was a piece of crap with a crazy landlord but it was the only place available that fit my wants I was there 6 years and build a good reputation and applied everything I had learned earlier from running the shop to marketing.
In 2006 I found the shop of my dreams 7500 building 1500 sq of office 6000 of shop space at first it was pretty good my landlord was sharing the shop space so rent was god and it gave me time to build the business, the building was awesome but it was a warehouse and not a auto repair shop so it had to be permitted here in California that set me back 30k but I was grossing 500k with 2 guys and myself so it was ok. Once the landlord left and I assumed the entire rent it became harder especially when a the would leave or I would have to let them go. Also due to the location of the shop it was hard to get customer to come in. I was not on a main road, there was a main road just down the street but still did not help me with drive by traffic. In 2009 the landlord sold the building to a group out of Korea and I was on the hunt again.
I found my current shop a 5 bay shop on a busy road with easy ingress and egress. I have 2 techs plus myself, one tech is still learning but getting better he came to me with little training but over the last 2 years he has come a long way, the second tech had his own shop but got tired of all the B,S so now he is working for me which is great. At the current shop my landlord is great that's a big deal for me, he painted my building a barn red so you can't miss it coming up or down the street. which has increased my bottom line.
So some of the hurdles I have run into that you need to consider
Money, how much in reserves do you have, you will need it to buy what ever this shop does not have, parts and equipment lifts, filters, fluids, air compressor diagnostic tools especially if you want to specialize. Plus all the licensces requied,, shop insurance workman comp ect.
Techs, really hard to find good techs they all say they can work on cars, but as someone said if they make a mistake it could cost you your home, your business. You need to do extensive back ground checks. I've had tech steal from me lie to me walk out on me, I've had them disaapear come in wasted do not stand for any of that.
Shop management tools there are a lot on the market you need to find something that is easy to operate and keeps in contact with your customer base. I use Mitchell shop manager with a few add ons this send out reminder text thank you text automatic but at a cost. You will also need either Alldata or Prodemand in helping with repairs Mitchell has labor and maintance programs build in to help with pricing.
Insurance and workmans comp. Very important if you get caught without this fines are $1500 per employee in California
Paying techs there is flat rate and hourly. In flat rate the tech gets paid on how much he can produce. If a job books out at 2 hours and the tech does it in 1 hour everyone wins but if it takes him 3 hours he looses. Flat rate is tough, the tech is working against the clock, especially when it come to diagnostic stuff or if there is no work he does not get paid.
Hourly is tough on the shop owner because if the guys are sitting around waiting on parts or no work then they are burning your money, but at the same time a good tech and busy shop will more then pay for himself on a hourly system. Here in Ca it is not legal for techs to be on a flat rate system, they must have a min. of $1600 take home every 2 weeks. for a 80 hr work week.
Shop is your shop currently zones for automotive repair best to check with the local city planning department. At my current shop that has been a auto repair building for 20 years I went to apply for a license at this shop and was told it was not approved for auto repair, I was shocked but after going through some old documents at the permitting department I found paper work stating that it was allowed.
Advertising there are plenty of things out there they all say they will increase business but the truth is 99% IS A WASTE OF MONEY. Things like cheap oil changes free tire rotations brake specials will bring in cheap customers one time and will only return when you have the next special. I use a company called WOW cards this advertises to my customer base which you want to do when you get there. Very affordable and great results. Mudlick mailiers expensive but they send mailers to a specific area and or car type. Of course a good website is important too
There are plenty of shop management training classes be very careful of these, they promise a lot and deliver a lot less then promised plus very costly. Most will offer a free seminar which are usually very informative also some of the suppliers like World Pac offer classes on car repair shop management ect
Hire a good book keep and accountant, I have a bookkeep that comes in 2 to 3 time a week to input to quicken and filing then once a year send everything to the accountant. Also do not fall behind on any state local or federal tax payments
Coming from a DYI background is hard but not impossible, you will have a pretty sharp learning curve, try and find good techs, buy good equipment, and good tools that will last you10 15 years, find good suppliers extremely important and keep the shop and office and waiting area as clean as possible goes a long way with customers especially if your a new shop .