Is there a conflict of interest between me and the university if I get paid on teaching others how to apply for the PhD positions in my university? I am a Ph.D. student. An application agent company approached me and ask if I could be a casual consulter on their platform and give some advice to the students who want to apply for the Ph.D. position in my country. Usually, there will be only 5 or 6 hours of workload a month and they pay 5000 dollars a year. The work is about that I teach them how to apply, like what they should focus on, when to write the emails to the professors, how to write the emails to get the professor's attention, where to search the useful information about the opening PhD positions. And the agent also asked me whether I could write the personal statement or even upload the application materials for their students. I refused as I think this might be inappropriate. I am a PhD student who wants to do causal work and earn some extra money but not a real application agent. But consultation work seems to be fine. I also see some Ph.D. students from universities even like Oxford doing the paperwork writing. I guess they pay a lot if you do such kinds of work. 

There are quite a lot of such companies. If you pay enough, they could deal with almost everything including paperwork writing, resume refinement, etc. for you during the application. I have already seen dozens of PhDs on their website. Some work on paperwork and some just work on consultation. Most of the PhDs’ major is English literature. I received a lot of emails from such companies. Usually I would ignore them except this one promised me that I could just do the consultation. Writing the personal statement for the others could be really annoying.

I think it is interesting as I could know some potential PhDs in my field and also I could get paid. But I just want to know if this involves some kind of conflict of interest as maybe I would help others apply for my own university in the future.
Three thoughts:

(1) It's hard to see how this is a conflict of interest if you have no role (even informally) in the admissions process. 

(2) Writing an applicant's personal statement for them is unethical. If you are advising students on the best strategies for dealing with particular individuals in your department, that also seems a bit like "insider information."

(3) You should consider the (not so remote) possibility that your department will become aware of your role on this platform. If you are okay with this, then it is likely ethical. You may even want to consider discussing it proactively with a trusted professor (e.g., the graduate program director).