I'm not too fond of the effects of the first 2 photo's, the first one is a bit weird, and the softening doesn't really fit the subject (usually you'd want flowers to be as sharp as possible).
#3 And #4 seem either out of focus or unsharp due to movement. For #3, 1/200 when using a 300mm focal length is too long. Rule of thumb is to at least have the same number for the focal length and the shutter time when shooting pictures from the hand; so in this case at least 1/300.
#5 is very sharp and easily the best one, but the composition could be better. The grey background isn't very nice to look at, so perhabs crouch down and pick something green as your background, instead of the tiles. Also, try to place your subject away from the centre to improve the composition. This book has a good chapter on composition, as well as information how to set your ISO, shutter speed and aparture:
Amazon.com: The Betterphoto Guide to Digital Photography (Amphoto Guide Series): Jim Miotke: Books