I had read a few introductory books on Foucault and did not find any of them very helpful. Yesterday I picked up this one by Jonanna Oksala, entitled How to Read Foucault. and liked it immediately after reading just the first two chapters. It is one of the books in the "How to Read" series published by WW Norton & Company, all of which are fairly short (just around 100 pages).
The book is very clearly written and informative, but what I was most impressed with so far is how quickly it succeeds in presenting Foucault as an intriguing and important thinker. Some of the things it highlights are instructive as to how one should read Foucault's writings. Here is an example:
Foucault once noted in an interview that, while there were truth books and demonstration books, his books were experience books. By this he meant that the experience of reading potentially changed the reader and prevented him from 'always being the same or from having the same relation with things and with others'. (p.24)
This is actually Foucault's own advice, and I am glad that I saw this in Oksala's book before I start to read Foucault's writings.