What are the best ways to get estimates on contractors before buying a property?

[Derrek J Hooyman]

I just started using the BRRR method. I bought a side by side that needed a little work. I was not as familiar then with the idea of BRRing it. However, the bathrooms were outdated. Thus I will cash out refi after I renovate the bathrooms. I have a decent understanding of flooring and painting now. The bathroom will be roughly 5k if I do the work with my dad.

However, I'm struggling to determine the costs of rehab if I would have someone do it like drywalling and more extensive BRRRs.  Any advice on how to get better at estimating my rehab costs?  Also are there any ways to get a better understanding of how much it will appraise for?  For arv, I can look at comps.  Guess I could get some connections to contractors as well/.  Any advice?