Remember, Depth of Field (DOF) is very different with close up photography. The closer you are to your subject the less depth of field you will have, even at small apertures such as f/22.
If you shoot at a wide aperture, such as f/4 and using selective focus on one part of the subject, the rest of the subject will go soft. Thus, the eye will be drawn to the sharpest spot.
Position the lens on the same plane as the subject, to maximize sharpness (parallel to the front of the lens).
First Blush of SpringTulip with lilac in pink, lavender and white.
Fill the frame with your subject.
Blush of a RosePink rose bud against white.
Try for soft colorful backgrounds using a long telephoto lens. Your camera needs to be closer to your subject than the subject is to the background shooting wide open (such as f/2.8 or f/4) at a focal length of 200 to 300 mm.