Going to do my first fix and flip this year in PDX, advice on education and resources

Hey everyone — planning my first fix-and-flip and want to get as prepared as possible before I pull the trigger.

Some background on where I'm starting from: I already own a house-hack property here in Portland — I live in the main house and rent out the ADU on a 12-month lease, so I've got some landlord experience and have been through a purchase/financing/inspection process, just not a flip yet. I've got a friend who's an active developer walking me through underwriting and renovation budgeting fundamentals, which has helped, but I know there's a lot I still don't know.

I've run some numbers on what a realistic first deal looks like: targeting something in the $400k ARV range, and once I account for the down payment plus financing and holding costs through the rehab and resale, I'm estimating I'll need roughly $130k on hand to comfortably secure the loan and carry the project. I'd rather spend the next year getting genuinely competent than rush in and let inexperience eat into that capital.

What I'm hoping to get from this community:

What resources — books, courses, podcasts, local investor groups — actually moved the needle for you early on, versus what turned out to be a waste of time or money?

If you could go back to right before your first flip, what's the one thing you wish you'd nailed down first? Underwriting accuracy, contractor vetting, financing structure, something else entirely?

For a first deal around a $400k ARV, does ~$130k on hand sound like a reasonable cushion, or am I under- or over-shooting?

Appreciate any advice — happy to share more on the Portland market if it's useful for context.