I have done this a few times myself and have a few basic recommendations:1) Make sure the seller owns the property free and clear and that it's very clear to both parties whether the arrangement involves a deed of trust or contract for deed2) If a balloon payment is involved, be sure to assess your ability to refinance and make that balloon payment in the future- optional extensions can help manage this risk3) Understand the tax implications if the interest rate is notably above or below market rates4) Get title insurance! 

There is a calculation that takes place and usually involves market based investments.  

Make sure every phone call with your brokerage is recorded (two party calls only or make notification of recordings if more than two parties involved) and every email and text is saved.

Ask about any unforeseen challenges that have come up (there always are, so not all challenges are a red flag), and overall let them know you're an involved LP who likes to be kept up to date on things

The final part of my degree involves a capstone project, and a requirement of the capstone project is that it be overseen by an industry mentor.

Lead Free involves more expensive tests and has a higher standard, but you're "one and done" in terms of licensing and registration.

and see what skills you might have to add some value as a side hustle.Things started to happen organically as I got more involved in the Chicago real estate market, and I am confident they will for you, too, in Seattle!

For your first project it is nice to be able to see it, talk with all the people involved, know the area, know the schools, know the employers, know the neighborhood, meet your trades, etc. 

Better off saving the 20% down payment + closing costs and reserves or getting a partner involved. 

I am not going to answer your question directly because it would involve teaching and there are a lot of points to learn about this.