Rose is an intermediate level pattern. It isn't exceptionally hard to create a rose, but if we really want it to look like the real one, getting all the details may be tricky. Although, please keep in mind, that roses actually do vary a lot. That means, we are solely responsible for how it will look like. At the beginning it's best to simply just follow the tutorial and try to create a rose, that the author of the tutorial has made.
We will get a better feeling on how to get into it, and then we can start using our imagination and add some extra details or even change the pattern accordingly to our liking. As long as we actually keep it looking like a rose, we cannot really go wrong here. Same goes for colors actually - we can create a yellow, red, blue or even a violet one. Obviously, the most popular color is red, but even with red we can apply all shades of red - darker red, lighter red or even a mix of colors and shades, if we feel like it.
It's hard to make the rose actually look bad as it's simply a beautiful pattern on its own, so as long as we keep it in a shape of rose, we will be okay, although there are many different improvements we can implement to make it look better - it's one of those patterns, that are fairly easy to create, but very hard to master.