Pillows are the easiest way to revamp a room, change the style add some color, and create a whole new feel to any space! 
Pillows really do have a dramatic effect on any room.  From sofas, to chairs, bedrooms, sitting rooms, family rooms and even outdoor areas, pillows are the easiest and most affordable way to liven up your space.  There is a few tricks to follow depending on your style preference, modern or more traditional.  

For the modern feel designers recommend using an odd number of pillows in the space.  Such as 3 or 5 on a sofa or bed.    Shape and size are are just as important for the style you want to create.  Keeping with the modern feel you should look for pillows that large enough to see a pattern or geometric shape, for solid colors the larger the pillow the better if will showcase of the pop of color.  Using an unexpected shape,such as oblong, will continue the modern. 
Selecting the right fabric and color is another way to fully bring the modern look together.  Limited color palettes are ideal for a modern, clean line look. Using geometric shapes, and prints on smooth tight woven fabrics, such as cotton and linen, will feel true to the modern home.  When choosing your colors look towards art work, accent chair, or rug to pull a color or two out of.
     Pillow trim is not normally used for the modern pillow, if you do choose to use it keep the trim color in the same hue as the main pillow color and style, less is more in this department.
A few Modern ideas found on pinterest
For those of you who love a more traditional style in your home we have a few simple tricks for you as well.  Symmetry is key here, using an even amount of pillows 2, 4, 6 and placing them symmetrical on a sofa or bed will create the traditional look and feel you are aiming for.  Use large 20-22inch square pillows on either side of sofa and add smaller pillows in front, shape does not matter as much.  Circle accent pillows can be used as well. 
         Traditional color and styles, on pinterest
Staying true to tradition style try choosing pillows in velvet's and silk.  Laying colors, fabrics and textures with prints in floral, plaids and paisleys will make the room feel alive. When using busy pattern such a floral and paisley pair them with pillows in the plaids, solid or strips,  using only 2 or 3 of the colors.  

This is were pillow trim comes alive.  In the traditional style trim is everywhere.  From braided edges, to pipping or cording, and tassel on all four corners of a pillow.  Try keeping large trim to the large pillows, and using smaller trim in the more delicate pillow edges. 
Traditionally colors in the style tend to me the warm colors of fall, reds, browns, oranges, greens and golds.  But pillows now come in all colors for any style, to add a more fresh modern feel pick lighter colors but in your traditional styles.