Ask her what she likes to do, try to identify exactly what she is good at and what she is not good at then use this information, expressed as positively as possible, to "sell" her. She also needs to have some ownership in this because whatever you write, she has to endorse at interview.
Explain to her that lying on a resume is unacceptable (even though people do it) but it is not only acceptable, but desirable to "blow your own trumpet". The resume should list all achievewments but for a beginner, tere won't be much there except where she has been to school and when, as well as what level of education she has reached. Include any extracurricular courses and activities ("tennis once a week for two years"; "ten-pin bowling league") as well as general interests and hobbies. If they are a bit of a worry for you AND if they are not in any way relevant, then leave the info out. You therefore don't put down as hobby, "Hanging around with friends on street corners to pick up guys, smoke cigarettes and deal drugs" even if the drug dealing shows enterprise, an ability to understand the workings of small business and a certain level of challenging people skills.
See? You can sell anything!
As I said, the resume is a list, sometimes in 3rd person, but there should be an accompanying letter in the first person which is targetted specifically to that job application which sells the applicant.
Actually, I think it will be a very healthy exercise for her, and maybe even for you, to go through the process of highlighting her strengths.
An example I can think of - "I would be very good in this job because I love to read books. Although I am still young and have many more books to read in my lifetime, I already have a deep interest in some areas which could be of value in recommending books to customers. I intent to continue reading, which will only broaden my knowledge and increase my usefulness to you. I have great computer skills, being experienced in [list the software she is good at and include social networking and especially any website design] and I'm also a fast learner with any computer technology I may not yet have had the opportunity to experience.
I would love to come and work for you because I enjoy meeting people and would prefer to complete my schooling from here on, from a more adult education perspective, studying while I work."
See how she feels about something like this. If you can help her feel a bit better about herself in terms of her chances, then she could go in to an interview feeling a bit more confident. Role-play it with her if she will let you, or see if a friend will role-play the interview process with her. Interviews are stressful for all applicants, even those who are well qualified and experienced in the workforce. I actually serve on staffing selection panels at difficult child 3's school and I've seen applicants for positions (including staff I know well who are going for promotion) being intensely nervous and sometimes making a mess of their interview. In one heartbreaking case, the staff member made such a mess of her interview for a promotion that we were unable to give it to her. The boss then decided to create a special position just for her, to help her get some sort of promotion because he knew she was up for the job, but she simply had not been able to do it via interview. Too nervous.
I hope this works out for her.
Marg