Wikipedia helpfully lists all of the Asterix books in the correct chronological order, rather than the one imposed by the publishers. That's good, because there is a clear development in the visual style of the books, and sometimes even the story. For example, the Gauls venture further and further afield over the course of the first few books; in Asterix and the Golden Sickle, Lutetia (Paris) is considered a long and difficult journey—but if you've been reading according to the publisher's order, they have already visited Egypt and Rome by that point. In the same book, Getafix is planning to visit the annual conference of the druids; the next book, Asterix and the Goths, is concerned with his kidnapping at that conference. The publisher's order inserts a volume between those two books, thus breaking the story continuity.
But what Wikipedia doesn't include are the various short stories—compiled in Asterix and the Class Act—in a chronology with the main books, which would be useful for anyone wishing to read the everything in the original order. So here's one, correct as far as I can make out from both the English and French Wikipedia sites. Short stories are shown in italics; books are shown in bold.
1. Asterix the Gaul (1959-60)
2. Asterix and the Golden Sickle (1960-61)
3. Asterix and the Goths (1961-62)
4. Asterix the Gladiator (1962)
- i. Birth of an Idea (1962)
- ii. Obelix's Family Tree (1963)
5. Asterix and the Banquet (1963)
6. Asterix and Cleopatra (1963-64)
- iii. Press Conference (1964)
7. Asterix and the Big Fight (1964-65)
- iv. How Obelix Fell into the Magic Potion When he was a Little Boy (1965)
8. Asterix in Britain (1965-66)
- v. Springtime In Gaul (1966)
9. Asterix and the Normans (1966)
- vi. Asterix and the Class Act (1966)
10. Asterix the Legionary (1966-67)
11. Asterix and the Chieftain's Shield (1967)
- vii. For Gaul Lang Syne (1967)
12. Asterix at the Olympic Games (1968)
- ix. The Mascot (1968)
13. Asterix and the Cauldron (1968-69)
14. Asterix in Spain (1969)
- x. Asterix as you've never seen him (1969)
15. Asterix and the Roman Agent (1970)
16. Asterix in Switzerland (1970)
17. The Mansions of the Gods (1971)
18. Asterix and the Laurel Wreath (1971-72)
- xi. Mini Midi Maxi (1971)
19. Asterix and the Soothsayer (1972)
- xii. Latinamania (1973)
20. Asterix in Corsica (1973)
21. Asterix and Caesar's Gift (1974)
22. Asterix and the Great Crossing (1975)
23. Obelix and Co. (1976)
- xiii. In 50 BC (1977)
24. Asterix in Belgium (1979)
25. Asterix and the Great Divide (1980)
26. Asterix and the Black Gold (1981)
27. Asterix and Son (1983)
- xiv. The Lutetia Olympics (1986)
28. Asterix and the Magic Carpet (1987)
29. Asterix and the Secret Weapon (1991)
- xv. Birth of Asterix (1994)
30. Asterix and Obelix All at Sea (1996)
31. Asterix and the Actress (2001)
[32. Asterix and the Class Act (2003)]
- xvi. Chanticleerix (2003)
- xvii. Obelix: As Simple as ABC (2004)
33. Asterix and the Falling Sky (2005)
- Dates are according to first publication; for books 1 to 20, the date is based on the serialisation in Pilote.
- It seems that Obelix's Family Tree was published in parallel with Asterix and the Banquet.
- The text of How Obelix Fell into the Magic Potion When he was a Little Boy was originally published in Pilote in 1965; the book currently available was first published in 1989 and includes new artwork.
- The story Obelix: As Simple as ABC is included in some newer editions of Asterix and the Class Act compilation volume.
Well, I think that's everything...