I read a book on memory.

I read a book on memory because I wanted useful information to enhance English my memory of the English language.

I usually think about what I want to learn books before I start to read a book.
At this time, I knew the objective: to enhance English  my memory. [or: "to enhance my memory so that I can improve my English."]
I searched for that topic from the in a book.

And then,I found a book about the topic about of mind-maps.
I heard about mind-maps before, but I haven't used it them and I don't know how to use it them.
I think it is useful for me to remember collocations.
Because it is difficult for me to remember collocations.

I will try to use a mind-map.