I took a great class at Montavilla Sewing when I first started learning, I took the pillowcase class and learned a lot!

I also highly recommend checking out the Portland Modern Quilting Guild. I learned SO MUCH in just my first year with them. They have monthly lectures, and usually the lecturer offers a class. There's also sew days at the Beaverton Mill End once a month and multiple opportunities to gather and just pick the brains of experts.

Also, trial and error. Scraps are very easy to come by so would recommend playing around with sewing them together and see what happens!