Manvisudan...you might want to re-post your dilemma in the design dilemma category and you will get more help with your room. Not too many people look at this "other" category.

You can work with your currant wall color or go more yellow - that is up to you. If you do decide to go more yellow. get some small inexpensive sample bottles at the paint store, paint some poster board and hang it on a wall for couple of days because getting the right buttery yellow can be hard. A soft yellow and lavender is pretty together but I also like the sea green. When you said a combo of modern and cottage - that made me think of beach cottages, which often have soft colors (including sea green) and unfussy, calm interiors. You can put a large painting up if you have the wall space for it. Many bedrooms have tall chest, dresser mirror, tall headboard and big TV, all which take up wall space. If you can hang the painting without it being crowded by any of the things I mentioned, it should look very nice. If you wish to do a curtain fabric treatment to a wall and you have the vision of what you want - then go for it. I had a friend who did that in collage - only problem was the yards and yards of fabric needed got rather expensive. So, I would start with finding bedding you love. Simple white is good, and not too expensive. However, you might find something else light that you love, or a quilt or throw for the bottom of the bed and the colors and shades might lead you in a different direction for wall color or accents. So bedding first, then curtains, then see how your wall color is and then add accents and art - although your painting can also be an inspiration for colors.

I see this post it really old, but if you haven't already, with blue roof, you can go with white or white toned wall paints, or give it a Moroccan look by painting the walls mustard and doors and windows white. This color scheme is very lively.

Hello Monika, I must say that concrete wall is fantastic! I see a large planter with a large leaved plant there.. I like Jonathan's idea, off white or shades of cream for the remaining walls and ceiling or even a subtle stone colour.. Then we need to talk textures! I think the sofa could work if you move it out a bit from the wall and layer it up with throws and add a couple of lovely cushions.. Warm woods would be nice too to balance the room.. Have you considered adding concrete to other areas of the home? There are some fantastic concrete chairs available both as a chair and bar stool.. Could be fabulous to compliment this room.. Cox and Cox did some pendant lights that were concrete with a warm edge detail.. You could create your own arrangement with a 5 wire ceiling rose and hooks.. A glass topped coffee table could be nice too.. Have a look at eBay or vintage shops.. Oh and one more thing... You can if you like the concrete wall find wallpaper for another room say that resembles what you have in the living room or even marble! It's fabulous and a feature you want to make the most out of! :))