I know that the time of the year the cuttings are taken, which varies depending on the species of plant, can be critical. According to the author of this article, the best time for home gardeners to attempt to root rose cuttings is in the cool months of autumn. (I apologize in advance if you've already read this article and not had success with the technique.)
I hope you will post about your various attempts. I would be very interested to learn what method ultimately succeeds for you. I have some very old rhodies and azaleas I want to propagate from cuttings, but my first attempt failed. At this point, further efforts will have to wait until next year, because I just had a total shoulder replacement at the end of March.
"Isn't it enough to see that a garden is beautiful without having to believe that there are fairies at the bottom of it too?" - Douglas Adams