This is a step by step colouring tutorial for a daffodil that I wrote for another site last year, and am now free to share it with you all today.
The Daffodil is a digital stamp by Toucan Scraps.
I have used Tria Markers from Letraset, these are alcohol based markers. Colour numbers Y418, O929, O949, 0567, 0346.
1. Coat the petal in a very pale yellowy offwhite [Y418]
2. Whist still wet, go over the top in the areas you want shaded in a slightly darker colour 
3. Add a little pale orange  to the places where the petal tucks behind another or the trumpet.
4. Go over the top of the entire petal again with the lightest colour [Y418] to blend. Repeat with all petals.
5. Allow to dry
6. Coat the entire trumpet with the palest orange 
7. Whilst still wet colour the trumpet with the next orange [O949] leaving only the bits you want to be highlights.
8. Use a bright orange [O567] to colour the main areas of the trumpet
9. Go over the top of the entire petal again with the lightest orange [O929] to blend.
10. Allow to dry
11. Colour the stamens [O346]