You scuff up existing paint for two reasons. First, you want to get rid of any oil, grease or dirt trapped in the top layer of paint. This is the stuff that cleaners and degreasers can't get off. The second reason to scuff is to set up a physical bond for the new primer and paint to adhere to. You want to give the old paint some tooth so the new sticks better.
To balance color, you must grasp the interconnectedness of color schemes. All color interactions are defined in the color wheel, and it has been used to build color schemes for centuries.
You can use vinyl on almost any exterior except previously painted wood. It works fine on wood shingles and shakes, asbestos shingles, brick, stucco, concrete and masonry blocks. One manufacturer says you can even put it on wood clapboard if the clapboard is new and unprimed.
To design a look with analogous colors, you can have any three colors next to each other on the color wheel. Successfully combining these colors in a room is one of the easiest, next to using monochromatic colors. In general you will want your design to use similar tones throughout the room except in the case of accent colors, which may be bolder.
HUE-VALUE-INTENSITY. Hue: Without getting too technical, and to put things into laymen's terms, hue is just another word for color. For instance, grass and leaves are two variations of a green hue.
Knock down texture is basically a orange peel that is sprayed on and allowed to "set-up" for a minute or two then gently "knocked down" by running a 6" drywall knife over it, "knocking down" the surface of the texture. Although knock down is a flattened version of orange peel, I suggest you do not use a spray can of orange peel, the knock down comes in its own spray can and the results are much better, again experiment before spraying it on the wall. However, If ever you apply any of the textures to the wall and are not satisfied with the results, wash the texture off immediately before it dries, then allow the wall to dry and try it again. Once you have the texture applied to your liking and you have allowed it to dry, you may want to paint the patches a couple of time before painting the entire wall, especially for walls where the paint to be applied will have some sheen. Multiple coats on these areas will make them blend in, unnoticeable, with the rest of the wall. You will know if the patches need more coats of paint, because the patch/texture will have absorbed the paint causing the spot to look duller than the rest of the existing wall.
Pick a brand you can trust Companies with their own high-street shops, such as Fired Earth and Farrow & Ball, and those that sell through the DIY giants are the most accessible. However, buying paint online is increasingly popular and can bring you a wider choice, especially if you live outside major towns and cities.