Home Improvement
Most of the time I just DIY for anything that's not massive, but when it comes to big projects like Roof/Foundation you listed Friends/Family/Neighbours I trust who have used them in the past.
Once I find a not shit contractor, I latch on to them and maintain that relationship.
Community mailing lists. Maybe Nextdoor. I’m much more likely to try someone that a person I know recommended. For instance, we have a very active school “bulletin board” mailing list and people ask for and receive recommendations all the time. I may not know the person making the recommendation personally, but we’re all part of the same community group and that holds some water for me personally.
Nextdoor is a real crapshoot depending on where you live, but if you have nothing else, it’s worth a try.
I'm a new homeowner and I also don't know how to find good quality contractors. For now I resort to posting on my city's subreddit to ask for recommendations. Also, recommendations from friends that have hired them in the past.
No idea. I get ecstatic over mediocre contractors who barely gouge. We've genuinely just started DIYing almost everything because if it looks "okay, I guess" then at least it didn't cost $8000 and I semi-learned a new skill.
Edit: our best contractor was from a random Google maps search for handy person. I picked a relatively new business with few reviews entirely because they were the only ones to call back. But they worked out great and I was happy with the work.
I think it is honestly trial and error.
Edit edit: the vibes you get from the in home estimate are helpful. If they don't try to upsell you at all, hire them.
In fact, the aforementioned best contractor we ever hired told me not to contract them to do something because it was a really simple to DIY. They showed me the exact kit to buy and told me how to do it. Theoretically he could have screwed himself out of money but we decided to do a bigger job than originally planned because of that move.
The best way is find a friend who had work done that you were impressed with and have them introduce you. That way you can get first hand experience about the quality and customer service.