Welcome aboard.
Model Railroader, the magazine, has a pretty good slogan for the hobby - Dream, Plan, Build. You’ve done some dreaming already, and part of your dream has already come true - you’ve got a whole garage to work with. But, before you start building, I think you need to spend a bit more time planning.
Yeah, it’s like a candy shop, isn’t it? There really is a lot of great stuff out there. So much, in fact, that it’s really tempting to over-buy. After a bit of this, most of us settle on a theme for our layout, and a location, and perhaps most important, an era. Back in the early 60’s, when I was a boy building my first HO layout, I bought mostly “modern era” stuff. Other equipment was thrown in, too. I guess I was vaguely aware that I never saw steam engines any more, but that didn’t keep me from running a couple in normal freight service on my layout. Now, though, I’m “early 60’s” myself, and my 40-50 year old equipment is “late transition” era. So, that’s what I model. No SD-40’s, no 80-foot autoracks, no container well cars. So, think about these things before you rush out and buy neat-looking stuff.
A garage is a big space. A 4x8 may be the right thing for you, but many of us will tell you that an around-the walls layout is a much better way to go, if you can manage it. Take a look at the space you’ve got, and imagine a main line running all the way around the outside of the room, maybe with a bridge on a swinging gate where your door is. Or, if that big garage door still needs to open, how about a layout around 3 sides of the room, either with a train yard at each end (point-to-point railroad) or a bulge at each end to accomodate a loop, giving you a “continuous running” railroad?
Finally, have you looked in your community for train shops and train clubs? If you’re lucky, you mi