This is so simple I'm not even going to show a picture of how to do it.
If you need to apply tiny bits of color to the edges of something, don't use a brush. That just ends with speckles of the color going onto other parts of your flower or whatever you're coloring.
Instead, stick your fingertip into the color, then rub the edge of the flower petal with your finger. That will let you put a tiny bit of color exactly where you want it to be. Like this:
I could have used a tiny brush and painted it on, but it's a heck of a lot faster to just rub it on there.
Kara Buntin owns A Cake To Remember LLC, online cake supplies at www.acaketoremember.com and www.acaketoremember.etsy.com