For the first one, the composition doesn't do much for me. With the cluttered background, I'd of taken a close-up shot of one of two of the buds rather than the whole tree.
Composition on the second one doesn't work for me either. I think the tulips are too far apart from each other to be effectively captured together as the subject of a photo. The depth-of-field is really shallow too and the focus seems to be on the second flower. For an image like this, I think it'd be better with all three in focus or at least the first two.
And, the last one is the best composed of all three. We have a clear idea of what the subject is (unlike the second image), and it's well-positioned in the frame. I'd of even taken it from over the tulip more so we see more of the colored center that's only hinted at in your image. Unfortunately, you missed the focus a bit. Again, with the shallow depth-of-field, this can be challenging. It looks like the camera focused on the edges of the petals, where-as I'd like to see the whole bloom sharp (especially the center, that's where my eye's drawn).
I hope that's helpful to you. Keep at it.