The varied Ghost in the Shell entries aren't a single chronology, so there's some flexibility in how you can approach it all.

The manga is the original entry, and you could read it whenever you want and it should be fine. Same goes with any of its sequels or reboots. I think most people have just seen the anime, if anything at all.

As for the anime adaptations:

The first one is the 1995 movie 'Ghost in the Shell' by Mamoru Oshii. This is the really famous one that inspired the Matrix. It has a sequel, called 'Ghost in the Shell: Innocence' by the same director. These movies are largely based on the manga but are different in their exploration of the themes behind the story, and just the overall general approach.

Then there's the TV series 'Ghost in the Shell: Stand Alone Complex', which has two seasons of 25 episodes each plus a movie, called 'Solid State Society'. This is in a separate continuity to the movies, but featuring the same characters. You don't have to have seen the movies to understand it, and the general reception of this series is very good.

Then you have the 'Arise' movies. There are 5 of them, and they're each about 50 minutes long. It's a re-imagining (kind of like a reboot) of the series, and it probably has the most mixed reception of all the entries.

Hope this helps!