To make the center of the tulip, cut a piece of wire the length of your tulip stem, plus 1/4 of an inch if you are going to plant it in a pot or a garden scene. Various tulips have different heights, a good length for a generic tulip would be 1 1/4 to 1 1/2 inches.
Paint the cut wires a basic green with acrylic paint and set them aside to dry. When the paint on the wire is dry, pick up some of the green paint with a toothpick or a straight pin, and dab it around the top of the wire. You want to have a small blob on the end of the wire, and a larger blob 1/8 inch down from the top. Blend your paint to give it the rough shape of the center pistil and ovary of a tulip flower. See the photo above. You may need to put an extra coat on the bottom of the ovary to make it round enough. Set the wires aside to dry. (I set them upright in styrofoam or scraps of floral foam).
When the painted wire is dry, take three of your stamens from the previous step and roll the yellow pollen end between your fingers to flatten it a bit. If the paint spread out too far, you can trim it off with scissors before you roll it. Dip the non pollen end in pva glue and gently press it to the wire just below the swollen ovary you made with paint. See the photo above.
Arrange three stamens evenly around the stem, then place three more in between the others. Set aside to dry.While these are drying you can make the petals.