This helps “separate” the subject from the background, rendering a blurred background. Or, try a “macro lens,” extension tubes or a quality “close-up filter” to achieve close focus.
Before “settling in” and going for your great shots of that flower, take several quick test shots and review them on your camera’sLED screen to be sure you’ve got the exposure correct and you’ve got just the right amount of blur or sharpness that your seeking with regard to your subject and to the elements in the foreground or background. Then, fine tune your adjustments, perhaps retest again, and then go for it!
Focus carefully on the flower (or the precise part of the flower) that you want to be tack sharp. It’s best to turn off the “auto focus” feature and manually focus until your eye confirms that the spot you want to be sharp is now in focus. Or, set your camera’s auto focus control to a single point and be sure that point is on the part of the flower that you want sharpest when you press the shutter.