Feel free to follow my thread if you want to know what the basics/must have's will be for a diy auto shop.
http://www.garagejournal.com/forum/showthread.php?t=305066&highlight=elephant
I myself have wrenched on cars as a hobby since i was a kid, employed as a tech, and an employer. I know what is needed and what is not.
-You need good lighting. Your main light source should be fluorescent. And have LED's as auxiliary/extra lighting. The reason why is most LED's cast a light that is different from regular "yellow" fluorescent light source. At least my eyes work better this way!
- Good power sources. Nothing is more annoying that tripping over wires day in and day out because you only have one source in the shop. Every corner should have a source, and several down by the sides of the shop.
- Good air. Place a good compressor outside and pipe the air in. More outlets scattered across the garage is good, but not a must. And you'll be glad the compressor doesn't take up precious space and that you don't have to stand next to it when it kicks in!
- Good workbench and vise. Make it sturdy. Don't cheap out on a vise either. You'll kick yourself in the nuts when it breaks on you one Saturday evening and you cant get a new (good )one until Monday. Depending on what work you are doing having a vise break on you can be very dangerous.
- A lift. And make it a 2 post one. No lift is more versatile than this type of lift. All work on a car becomes so much easier when you have a lift.
- A shop press. 20tonnes. You'll thank yourself you have one each and every day, even if you don't use it that often. When you need it, it is that good. If you intend on working on rear axles you will need one that i standing on it own. Not the one you put on a table and is half size.
-Storage. Keep things of the floor and instead put it on shelves and in cabinets. Makes less of a clutter. Will free up space in the shop and inside your head.
-A crane for pulling engines. Preferably one that folds away.
-A welder. Pick your poison MIG TIG etc. I like MIG as it is easy to work with.
-A (big)jack and at least 2 jackstands. Having a smaller jack as a backup becomes handy when you need to mate an engine and a transmission in the car. The smaller jack can be used to set the angle of the trans, while you wiggle around with the crane until they mate!
-A gearbox lift. Make it a strong one for when replacing various bushings and spring on the car. 2 lifts would be better. Especially for when making custom (dual) exhausts
-A bench grinder
-A drill press.
-Oxygen and gas setup to heat stuff that wont come loose.
Nice to have: A metal lathe. When the day comes that you need it, you be grateful you have it. Also, lathes are fun. You can do all sorts of cool stuff with a lathe.
Aside from various tools these are the things that come to mind when i think about that basics of any good place to be. Sure, there are lots of other stuff im probably forgetting such as venting and decent parking options outside the shop. But the above will get you very far. Not only as a DIY but also as professional.