If you need a bit of help with grammar, I am publishing A Quick Grammar Guide online.
You can access it by clicking on this link.
It is still a work in progress, but I guarantee it will be helpful!
Materials for this guide were developed for seminar-workshops I designed and delivered as Cynthia Lapeña, Cynthia Rueda, Cindy Rueda, Cynthia Amador, Cindy Amador, and Cindy Lapeña. To simplify things, I am now simply using Cindy Lapeña.