So How many is too many question is really a matter of the decorative style you are going for and personal preferences of course. Don't forget to keep in mind your floor and wall colours, current furniture style and overall look of the current décor and interior of your place. Here’s a tip for choosing the right number of solid coloured versus patterned pillows. For solid pillows, go with an even number – 2 or 4 for example. For patterned pillows, choose an odd number – 1 or 3. Nobody knows why this works, but it does.
I like mixing bright colours with neutrals to create to create contrast. Make sure your cushions don't match your sofa - not a good look and clearly not very creative. The exception to this is if you have a large sofa or sectional. For example eye-popping turquoise/pink/orange pillows are especially noticeable among light furnishings and pastel accessories. I have turquoise ones in my bedroom mixed with white pillows
You can also add some texture to the sleek room with cushions made of different fabrics and textures.You want to look for the same aesthetic in texture while still adding fun and dimension to the room.
One approach is to use cushions in a solid colour. Try picking up on a complementary colour in the sofa, drapes or rug. If you do have solid coloured cushions, make sure they are pulling together other colours in the room.
Going super bright will cheer up any space and add some personality to it. Mixing brights with neutrals or brights with brights of different patterns and textures will do the trick. Easy way to spice up a boring room.
If you buy a patterned toss cushion, make sure that pattern picks up at least one colour that is already in your space. Pattern incorporates colour in a more intricate way. There’s a myriad of patterns to choose from: stripes, floral, abstracts, polka dots. A throw on the corner of a sofa is a beautiful way to tie all your colours together.
I'm also a big fan of large pillows like this one for example, it will give a sense of dimension to your space
Selecting cushions of different shapes will also add more dimension and structure. And will also add a bit of fun to your space
Bed pillows and cushions
To arrange the pillows for the right look, start with a couple of large pillows against the headboard. You might have noticed how comfy hotel bed can be. It is usually due to a high quality mattress and amount of pillows and cushions different sizes. So through some pillows large to your regular size on your bed and decorate with nice cushions to match your over all style
The easiest way to buy new cushions is to take a fan deck of paint colours (you can get one in any paint store, and every home owner should have one) and find the paint chips that match the furniture already in the space.