Well for windows and doors you'd use gloss or satin finish paint in white and it shouldn't really be different to your white wall paint in colour , if you used the same shade of white from the same company.

A picture is worth 1,000 words of advice at Houzz. Please comment here and use the Attach Images button to add pix of the space where you have the dilemma. Do you have an inspiration picture, piece of art, rug or fabric that is determining the color for each bedroom or are you just grabbing these colors out of a hat? White goes with all of them.

I love your wall color. A green print bed spread with yellow and purple colors would look great with your wall. Can you move the mirror/night stand to another wall. It looks crowded in that corner. Then mirror glass side tables with drawers would really sparkle against the purple wall. And then art on the walls.This is not a bedroom but you can see how green, yellow and purple go together.

What soft furnishings do you have. You could pic out one or two colours as an accent colour and use that as your Base for the curtains. I currently have cream hessian walls and have a duck egg blue and chocolate curtains. I'm currently making matching Oxford cushion covers for the settees . If you can't find what your looking for ready made buy the fabric and have bespoke curtains made for you.