6 imperatives for a killer tumblr:
1) Quality Content: I only share what I and my followers like
2) Infinite scroll: the only buttons I push are ‘Like’ & ‘Reblog’
3) ‘Like’ & ‘Reblog’ buttons on every post on your homepage
4) At least one share button for another social network
5) Exploit the full width of my computer screen: envelop me
6) Forever invade my memory with a beautiful design