If making a single outline around a flower, I will typically just start and then run a few small stitches over the beginning stitches when I get to the end. This doesn't make much of a bump and saves having to hand-bury thread ends. I would definitely do this if making a single outline around lots of flowers.
If doing echo quilting, however, where I want to make multiple outlines of the flower each 1/4" apart or so, I would consider doing it continuously. Once I have made small stitches over the beginning stitches, I would just sew a slant line out 1/4" inch and start the outline there. It makes a slight difference in the overall quilting that may or may not work for a specific flower.
For a large flower, I have actually using my walking foot to do echo quilting. It's a little slow because you have to stop and adjust the sandwich under the presser foot frequently, but you do get even stitches this way. The flower has to be large so the curves are fairly large. For a small flower you'd have to stop after every one or two stitches and it wouldn't work.