I think another obvious strength that INFPs often possess is writing. I write some crap poetry and short stories here & there, but I have also written articles for magazines & done quite a bit of copy writing for ads (one of those unexpected things you end up doing in print design).
I consider myself a bit of a visual artist, being a graphic designer, having some sketching ability, dabbling in painting, and generally having an eye for aesthetics in my everyday life (dress, decorating, etc). If I think I have undeveloped talent & could be a much better designer, but I need to apply myself more, especially in the hands-on aspects. I'm idea focused and can lose interest before even beginning a project. Basically, I am lazy!
I'd say that's a big difference between me and the ISFP artists I know. They enjoy the process itself and are more inclined to dive into it. They just do stuff for fun, but I need a reason. I create things with some idea in mind, even if it's just a vague feeling,; starting the physical creation of an idea takes a lot of motivation (that I often do not have). I find when I am actually doing it, I enjoy it a lot though.
Some other differences between ISFPs' art & mine may be that I tend to be more conceptual, and the ISFPs will be a bit more literal. For instance, my ISFP step-dad has better technical skill than I do, but he tends to take ideas from things he has seen & adds his spin on it. I have more original ideas, so much so that he has tried to "steal" from me (actually he asked, and I said "no" - haha). Strangely enough, I have more elegant, refined taste than most ISFPs I know; although, that could just be because I am a woman and they are mostly men.