Richard,
Welcome to the forum!
I think you have done all the right things so far – mainly because they are broadly similar to what I did . I have also benefited from are getting an opportunity to drive an engine on a track, confirming that I am interested in both building and running a model locomotive. And I have made contact with other members of this forum in my local area, learning loads from visiting them in their workshops.
When I was faced with your question, the answer I chose was to build something I want to own, in my case a modest 5" gauge locomotive, just because personally I cannot muster any enthusiasm for the 'standard' training pieces or engine kits. I'm 4 months in and have not so far regretted my decision; there are lots of components I've treated as training pieces (the Buffer beams have been been built twice , don't ask) before moving on to the more expensive parts. The benefit is that once I have completed a component to my satisfaction, I am a small step nearer to what I want to achieve.
I'm sure there will be other answers to your question, it's all just a matter of choosing which one suits you, your budget, your objective and your time available.
Best regards
Mike