Did she not do any kind of work experience placement at school?
Agree with teacher for reference, or a professional friend of yours as a character reference.
For experience, mention no formal work experience as yet, but various skills that are likely to be useful to the job. E.g. attention to detail, good organisation skills, good timekeeping etc with an example of proof for each one.
A lot of employers hate hiring teenagers because they are almost always late and unreliable, so she needs to prove she's not like that.
6 jobs isn't very many, try to apply for 20+.
Agree will be much easier in the next few months with Christmas temp jobs.
Also ask school/college if they have any placements or job opps with local companies, some do. I got a much better job than I would otherwise around that age - working at a tech company that paid much better than local supermarkets.