A woman asked me what she should focus on first being a new Muslim, what should be her priority now?
Learning Aqeedah is most important but learning it alone without a teacher is difficult and could lead to misunderstandings. My advice to you and to every Salafi sister is to try to help the beginners by teaching and explaining to them what is essential to know. So if she finishes a book, like thalathatul usul (the three principles), she will be able to read aqeedah books afterwards on her own.
Believe me, you will benefit yourself a lot if you start to teach sisters whom you know. This teaching has a very special blessings and Allah will grant you more and more knowledge and understanding as a reward for doing that for your sisters. Allah is The All-Thankful.
The books by themselves are most probably not effective as they need to be explained and facilitated to the beginners.
Teach her the meaning of Tawheed and try to teach her how to love Allah and how to glorify Him, The Most High.
May Allah use us all in the best thing ever, the profession of the Prophets, spreading and teaching Islam.