You mentioned higher wages, but I am wondering how those higher wages could be implemented.
That being said, I would say that grants are definitely a big help. Loans and grants are very appreciated, especially grants, since loans eventually have to be paid back. Grants mostly help women access those fields of study. Awarding grants that target women in particular can obviously help.
It's interesting to note that one study—which was not carried out by me—looked into the chosen fields of study. It compared the way boys and girls choose their field of study. By identifying the various factors that influence those decisions, the study showed that girls place far less emphasis on the wages they could earn once they graduate. Boys actually focus more on the wages than girls do. Is that because girls are less informed or because they are interested in other considerations? That is less clear.
According to the same study, the parents' education is a factor that greatly influences young girls' decision. In that study and in a number of other studies I have read, the parents' expectations and aspirations regarding their children have an influence.