I'd say there are many pros and cons for newer and older as a starter (I went older, 84 Nissan 300ZX Turbo).
Newer (lets say 15 years or newer so we are talking about 1996+ which should have ODB2)
- OEM Parts Availability
- More Cars in Junk Yard to pull parts from (dependent on production numbers, but still more than older models)
- Less wear and tear
- ODB2 to get feedback of vehicle status
- Less drum brakes!!!
- More electronics, depending on your background, you may have catching up to do on the tech as well as the mechanical
- Complexity of systems, safety and emission regulations have added A LOT of equipment to newer vehicles
- Engine bay space, almost always when comparing a new and old model the old model looks to have a huge cavernous engine bay.
- Originality/Lack of Nostalgia, more of them on the road makes you less special, not a mechanical issue but I think it impacts how much you care about the vehicle.
Well, most of the above for the newer, just reverse the pros and cons and those are the Older list primarily.
One thing that seems to be heavily debated is Carburetor VS Fuel Injection (FI).
- If you learn on FI, then carburetors are a mysterious beast that make no sense.
- If you learn on carburetors, then FI is a mysterious beast that makes no sense.
I say, get what peaks your interest the most, that is what you are going to care about the most and have the desire to get right.
Find a Car Club
Having an active car club community for the vehicle is my biggest recommendation I can give as far as a deciding factor. Look for one that hosts Tech Sessions or Garage Days or whatever name they come up with. These are events organized by club members to get together and work on their cars. It can be one person's car accomplishing a specific project (mine has done the clutch package on my car, suspension on another members, adjustable sway bars, brake pads and bleeding, etc) or it can be everyone showing up with tools and intended projects to accomplish and sharing knowledge and assistance accomplishing the projects.
A car club should be very welcoming if it is a good community. You can visit their meeting as a guest before you've even purchased a car to get to meet some people, get an idea of what the community is and ask them about advice on picking the car (someone may even know of a good one for sale). They will be far better information resources on the specific vehicle then we could ever try to be. Also see if they have any public events, car shows, cruises, etc that you can go and see their cars all prettied up and on display. This is another great time to talk to them and get more information.
If you look through my other answers on the site regarding learning you will notice a common theme of, along with specific advice, I mention getting into a car club. I've only been actively doing my own car repairs and maintenance since the beginning of this year. I had bought my car last year and joined the local Z club. In March we started doing monthly-ish (whenever we have time and a project) Tech Sessions starting on the clutch, flywheel and adjoining bits and pieces on my car. So my first ever car project was dropping the transmission in my car. Having the knowledge and support of 3-4 fellow club members and a fully stocked garage for the 13 hour project was invaluable. No matter how much reading, forum searching, etc I had done I couldn't have pulled the job off myself (If I had read online to get the transmission to line back up you had to wiggle the transmission jack back and forth sideways while pushing forward to get it to rotate to line up the splines to slide back in, I wouldn't have believed it, but that is what we had to do).
Through the Tech Sessions with my club, now I've been able to do a lot of work on my car myself (after we did a fellow members brake pads and bled the brakes, I went home and did it on mine) and am able to be sharing my experience with people here because of what I've learned.