Marjorie Harris is a very talented artist and teacher whom I admire very much. I love her video tutorial where she shares her freehanding method of painting flowers.
She makes painting roses look so easy but it is only simple for talented artists like her.
Here is one of these very instructive tutorials. I hope you will enjoy it the way I do.
You may want to have a look at Marjorie Harris's website too.
And now, my favorite, from artist Maneco Araujo:
See also my rose drawing lesson: how to draw a rose in five steps.