I speak to a lot of beginners setting out in railway modelling. I do my best to dispense helpful advice. The main thing I say is "Start small".
Sadly, by the time I say this, it's often too late. Lofts have been boarded out. Vast empires have been embarked on.
I have an analogy. It's a bit like taking up baking and deciding that the first thing you'll have a crack at is a wedding cake.
It can't end well.
My advice - try and batch of cupcakes first.