these are my opinions on what helps improvement the most:

beginner:
reading, studying - 40%
playing - 10%
analyzing - 30%
watching more experienced players play (and learning why they do the things they do) - 20%

intermediate:
reading, studying - 20%
playing - 20%
analyzing - 40%
watching more experienced players play - 20%

advanced ("expert"):
reading, studying - 10%
playing - 30%
analyzing - 10%
discussing theories/topics with other advanced players - 50%