Question on arranging flowers

I have a 10' x 50' stretch of yard between the sidewalk and the street that I'm planning on planting about 10 different flowers in. This is my first serious flower bed attempt. I don't want to just have clumps or rows of these flowers but I can't think of a way to make it look more natural. Recommendations? Do I just mix all the seeds together (based on planting times of course) and sprinkle them about?