#1 Has quite a bit of noise (look closely at the green at the top).. The lighting is pretty dim and poor, I think with some sunshine on it, you would have had a good go at it.
#2 would be better if the lighting was even and the highlights weren't so strong. With white and yellow, highlights can cause sensor overload.
#3 Again, you have a whole bucket of noise. The flower is also a bit out of focus.
I would say choose the time of day carefully, and as you walk around looking for flowers, look at how the sun/light is hitting them and position yourself to get that shot of the warm light painting over them. Also look for flowers that are solitary with nothing behind them for a good ways, a dark background is even better. Then get low on them so you isolate them.