Welcome Bart
I dove into this hobby just less then a year ago. I currently have a main line installed having just finished it this past April. I did a lot of research and figuring out what to buy from whom. Almost everything I own is new, wanting very specific engines, cars etc… and finding it more convenient then searching the web for used.
There are a lot of informative sites out there I used that really helped, aside from this forum.
The articles here are great, https://familygardentrains.com/ thought some a bit out dated when it comes to what is available to purchase.
I have also watched the UK series Mark Found - Garden Railways twice. https://www.youtube.com/watch?v=qcMe1QKuEyQ&list=PLYdqgmYJKJx3lLZEfkrCwuQmkljnX0T3s It was good for getting ideas and also what is involved in setting up a railroad.
Greg Elmassian also pointed you to his site which I also found quite helpful for information.
I have gone with almost completely USA Trains track and trains. I liked the Canadian engines they offered and I liked that they are easy to convert to battery via Airwire’s products.
I did buy some LGB initially but didn’t like it and ended up selling most of it. I liked the look of the USA Trains stuff more.
Let me know if there’s anything else I can help with. I have my build log on here as well that I continue to add to. It covers the layouts I chose as well as how I built the layout.