Decorating our bedroom

Seeing we live in on base housing, we are limited to what we can to do to 'sass" up our home. If we paint the walls, we have to repaint them which doesn't appeal to me! So despite the lack of color, I still want to decorate our house and make it as homey as possible. Ive always been attracted to the nautical/simple style with the colors white red and navy blue. In particular, our bedroom, since Ive been back, has seemed like a white dull cell hahaha. We have a beautiful dark brown bedroom set and dresser but the walls are completely white. I have a navy blue striped duvet cover and curtains so I have been trying to find some simple, personalized and colorful items to add to the wall.

I would like to get three wooden letters to put above our bed as a monogrammed in either a red or navy blue, a pop of color on these white walls. I am also considering  other simple wall art to put on each side of the window. If you have any ideas, I would love to hear them!!!

Here is my inspiration: