I'm almost scared to enlarge the pics... they make my eye water.
Kidding.
Well, I got a rather cheap camera, some Canon "one touch easy" and it's got a feature for close-ups, with I think a flower or even two flowers coming up on the screen... what I do (and I am not sure it's a rule), I always push the button just a little bit until I can hear something is going on, and it zooms on the flower, sometimes it missed and the frame in the middle of the screen blinks in red (trying to tell me "try again, Calin!") and then I move the camera away and try again. As suggested :)
When the zooming works and the frame turns green i slowly push the button all the way.
When it's red, it usually focuses on the surroundings, like in your pics.
If I keep the camera in the same position but just release the button and press it again, usually no better result can be expected.
I have to take the camera away, and try again.
I think there is a limit...meaning, if it's too close to the flower, it will never get a clear pic.
By the way, the yellow one sure is a beauty with all the red stuff hovering around.