Unsolicited. That sounds strange and desperate... definitely newbie.
Your friend needs to establish a relationship with someone before submitting to them. They should have a connection. I do not solicit for subs. They normally ask me if they may serve, because they know me as a person and would feel comfortable submitting to me.
There are a lot of dangerous people who call themselves doms.
My perspective is that the Dom/me or Master/Mistress earns their title, and the sub earns the right to use that title in his/her service.
The relationship between D/s is built based on the interests of both parties. Blind service is never good, and could put your friend in danger. Online relationships are sometimes a first model for the way she/he will allow himself/herself to be treated in real life. Tell your friend to take care, educate herself, and make wise choices.