Tintin, created by Georges Remi under the pen name Hergé, appeared the first time as comic strip in the Belgian newspaper "Le Petit Vingtième" (Tintin in the Land of the Soviets) 80 years ago (10. January 1929).
Personally I do not appreciate the first three albums too much because Hergé had to think from week to week to create a new strip for the newspaper and you cannot really speak of a story line due the fact that everything is too improvised.
Starting with Cigars of the Pharaoh Hergé did a lot more of research and the storyline get clearer. I especially enjoy reading the books from The Secret of the Unicorn on... with Haddock as impulsive counterpart to the more rational Tintin
What I find so fascinating is the fact that you can read the books in different ways : as a child you can simply enjoy the story with his slapstick humour as adult you can re-read them with a new awareness and try to understand sophisticated satire, and political and cultural commentary and admire how how accurate Hergé was with his subject matter.
You probably need a key to the time and world of Tintin. I highly recommend Tintin. Le rêve et la réalité. L'histoire de la création des aventures de Tintin. translated in English. An amazing source of information about Hergés sources, influences, historical backgrounds and a lot more..
If you don't want to buy the book you might still find this article very helpful :
Examples of Contemporary Inspiration in Hergé's Work