Mask the stamens.
Once masking is dry, with clean water, pre-wet the yellow areas within the flower as they appear in the photograph, then drop in Aureolin. By dropping in your paint I mean just let it lightly flow out of the brush and onto the wet paper. Do this section by section as shown in the image below.
Add some stronger Cad Yellow Pale with some Cad Orange in the deeper warmer areas. Paint shapes within hard edges, soften edges with damp (not soaking wet) brush were there is no hard edge.
Continue until all areas are covered with whatever yellows are needed.
Wait for this to thoroughly dry.