I'm in my late 20s and have invested my own money in a few buy and hold properties that are profitable. I'm curious how you'd suggest structuring future RE investments with family or friend money... Flat rate of return? A percentage of profits?

I've always invested my own money but would like to continue investing in RE now without having to wait while I save up money.

That's pretty vague, what I suggest is that you partner with family the same way you would with any other investor and keep it business like, be specific as to the understandings, the goals, the splits of profits, tax deductions and when and how a property is to be sold.

The deal at hand often dictates what the best structure might be starting off, it's the trial run in such arrangements, so take greater care that you select a good property.

My other advice is to make sure they get paid before you do! :)

I've done well finding properties in the past. My last 3 are buy and hold and cash flow positive. The issue is that I have no examples of how investor deals are structured so I don't have a good starting point and I'd be shooting in the dark setting up that arrangement.