The most likely outcome is that you will be ignored with a "blind" contact and won't get a reply to any email. I've gotten a lot of mail from "students" wanting to "join my research group" when they obviously have no knowledge of what it is and no relevant background. It will be difficult to be heard through this noise. They normally attach a CV, but it never gets read.
The suggestion of first learning about what the professor is interested in is a good one if you can possibly do it, but, just as you suggest, that will be difficult.
You mention that the article you read is about doctoral admissions but don't say if that is what you want. For undergraduate admissions, however, I think that the normal admissions process through the university is all you can achieve.
But if it really is doctoral education, then, I hope you have a suitable undergraduate education and maybe a Master's Degree, so that you already show some level of specialization.
If this is the case, you might be able to find a few professors who do things of interest to you just by reading the titles and abstracts of a few articles. Narrow them down by searching in specialist journals or conference proceedings. If you can understand the abstracts and if your background is applicable then you might have the basis for a contact.
If you can find a suitable professor or two, and also find the "introductory" courses they teach (at the desired level), you could express your interest and ask if they would send you a reading list for such a course. This would give you a way to explore the topic more deeply without going into state of the art research articles. But you have to be able to get a reply.
But if your degree is in Pneumatic Hydrology and you are applying to someone in Mathematics or Computer Science, you won't get a reply.
I'm assuming here that you are not currently in the US so it wouldn't be possible for you to attend a US conference in the field you want to study. Many conferences have "student volunteers" who do low level tasks at the conference but allow you to attend sessions and meet people. This might be better if it is feasible. You would probably need a sponsor for travel, of course.
You also indicate that you may be a weak or borderline student. This makes it much harder unless you have done some especially good piece of work in the common field that will be of interest to the professor.
Finally, if you have access to some professor locally who really believes in your potential and who has contacts, perhaps he or she will be willing to introduce you to someone who is willing to consider you. A letter from someone the professor met at a conference previously is going to be read, and curtesy will require a reply.