Unfortunately, there is little that you can do for her. The majority of her choices lie in actions she has to do herself.
There are several different ways to come to USA, and of course they may arbitrarily be divided into:
1) Visa lottery
2) Education (mostly non-immigrant but hold strong possibilities for receiving a greencard based off job offer post-graduation in specific fields)
The visa lottery is a program where individuals are randomly picked by USCIS. The chances of winning this "greencard lottery" (as it is known) are slim.
Education allows an individual to come and study in the USA for a period of time, and sometimes, the individual may be able to receive employment by a US sponsor employer, although there are no guarantees. She may also get married and adjust to a greencard this way. This is perhaps one of her better chances - to come and study.
Employment is generally considered a painstaking process and unless you have a technical degree or medical degree - along with a job offer - there is really little possibility of actually getting a visa based on employment. The bar is set very high. Given that she only has a high school diploma, the chances of her receiving a work visa are slim to none.
Marriage is the "easiest" assuming that the marriage itself is genuine. USCIS will review the petition for genuineness. Some get rejected. This is another good option.
Asylum is really not an option for someone from Jamaica due its reasonable stability and lack of sectarian violence.
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