decorate / mix and match pillows

I have a confession. I am pillow mismatching challenged. I love photos of mismatched or mix and match pillows, like these:

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While I like to think that I have a good eye for decor, every time I try to put together a grouping for my own apartment I feel like it doesn’t look right. I think the only way to go about this is to buy one or two that I love and keep adding from there. Any advice?