This house is the RGT kit Victoria's Farmhouse. It has milled "clapboard" MDF walls. First, I had to square up the window openings. Justin helped me with that.
I gave each piece a light sanding and wipe down with a very slightly damp cloth to remove the dust. I used Behr interior latex paint with primer tinted a nice soft pink.
After the second coat of paint, use a finer grit sandpaper, about 220 grit, to smooth out the last little bumps and grooves. I like to sand, wipe off the dust, then test the smoothness by touch. It should feel very even, smooth and satiny. The third coat should go very smoothly and dry with few imperfections. Carefully stir the paint so there are no bubbles in the final coat.
Next, assembling the house foundation.